How can I check for an active Internet connection on iOS or macOS?

Question

I would like to check to see if I have an Internet connection on iOS using the Cocoa Touch libraries or on macOS using the Cocoa libraries.

I came up with a way to do this using an NSURL. The way I did it seems a bit unreliable (because even Google could one day be down and relying on a third party seems bad), and while I could check to see for a response from some other websites if Google didn't respond, it does seem wasteful and an unnecessary overhead on my application.

- (BOOL)connectedToInternet {
    NSString *URLString = [NSString stringWithContentsOfURL:[NSURL URLWithString:@"http://www.google.com"]];
    return ( URLString != NULL ) ? YES : NO;
}

Is what I have done bad, (not to mention stringWithContentsOfURL is deprecated in iOS 3.0 and macOS 10.4) and if so, what is a better way to accomplish this?

Biamonte

You could replace the last line with: return (id)URLString; (Omitting the cast will also work, but might give you a compiler warning.) – Gadid

Rather return (BOOL)URLString;, or even better, return !!URLString or return URLString != nil – Amoeba

I don't know what your use case is, but if you can it's preferable to try the request and handle any errors such as a lack of connection that arise. If you can't do this, then there's plenty of good advice here in this case. – Saville

Your solution is clever, and I prefer it. You can also use NSString *URLString = [NSString stringWithContentsOfURL:[NSURL URLWithString:@"https://twitter.com/getibox"] encoding:NSUTF8StringEncoding error:nil]; To get rid of the annoying warning. – Slantwise

try using Reachability class from the below link, it will work for you github.com/tonymillion/Reachability – Voronezh

For those recently finding this answer: stackoverflow.com/a/8813279 – Mesothelium

Or try this singleton class so you can set a timeout to avoid hangs in 100% packet loss scenarios. github.com/fareast555/TFInternetChecker – Cottingham

The fastest and easiest way to check connection - https://mcmap.net/q/46287/-easiest-way-to-detect-internet-connection-on-ios – Glasswort

https://mcmap.net/q/46288/-how-to-check-internet-connection-in-alamofire – Sharenshargel

Answer 1

Important: This check should always be performed asynchronously. The majority of answers below are synchronous so be careful otherwise you'll freeze up your app.

---

Swift

1. Install via CocoaPods or Carthage: https://github.com/ashleymills/Reachability.swift

2. Test reachability via closures

   let reachability = Reachability()!
   
   reachability.whenReachable = { reachability in
       if reachability.connection == .wifi {
           print("Reachable via WiFi")
       } else {
           print("Reachable via Cellular")
       }
   }
   
   reachability.whenUnreachable = { _ in
       print("Not reachable")
   }
   
   do {
       try reachability.startNotifier()
   } catch {
       print("Unable to start notifier")
   }
   

---

Objective-C

1. Add SystemConfiguration framework to the project but don't worry about including it anywhere

2. Add Tony Million's version of Reachability.h and Reachability.m to the project (found here: https://github.com/tonymillion/Reachability)

3. Update the interface section

   #import "Reachability.h"
   
   // Add this to the interface in the .m file of your view controller
   @interface MyViewController ()
   {
       Reachability *internetReachableFoo;
   }
   @end
   

4. Then implement this method in the .m file of your view controller which you can call

   // Checks if we have an internet connection or not
   - (void)testInternetConnection
   {
       internetReachableFoo = [Reachability reachabilityWithHostname:@"www.google.com"];
   
       // Internet is reachable
       internetReachableFoo.reachableBlock = ^(Reachability*reach)
       {
           // Update the UI on the main thread
           dispatch_async(dispatch_get_main_queue(), ^{
               NSLog(@"Yayyy, we have the interwebs!");
           });
       };
   
       // Internet is not reachable
       internetReachableFoo.unreachableBlock = ^(Reachability*reach)
       {
           // Update the UI on the main thread
           dispatch_async(dispatch_get_main_queue(), ^{
               NSLog(@"Someone broke the internet :(");
           });
       };
   
       [internetReachableFoo startNotifier];
   }
   

Important Note: The Reachability class is one of the most used classes in projects so you might run into naming conflicts with other projects. If this happens, you'll have to rename one of the pairs of Reachability.h and Reachability.m files to something else to resolve the issue.

Note: The domain you use doesn't matter. It's just testing for a gateway to any domain.

Bombazine

When they talk about the host being reachable, they are actually talking about whether or not a gateway to the host is reachable or not. They don't mean to say that "google.com" or "apple.com" is available, but moreso that a means of getting there is available. – Bombazine

My checkNetworkStatus method is not getting called.. I'm retaining in the init method. Anyone else have this trouble? – Inexactitude

Ah - have to call it manually, since the internet connection isn't "Changed" right when you start. In my ConnectionService init: _internetReachable = [[Reachability reachabilityForInternetConnection] retain]; [self checkNetworkStatus]; works. Thanks! +1 – Inexactitude

@gonzobrains: The domain you use doesn't matter. It's just testing for a gateway to any domain. – Bombazine

This example is using internetReachable, hostReachable as class members, which, for me, raises memory errors. I solved it by following Apple's example and accessing the object returned with the notification in the observer method. – Einstein

Tip: Make sure no other libraries you have added already contain Reachability. I had linker errors only to realise Sharekit already had Reachability .h & .m included so I had them in the project twice. – Pubes

Does WWAN include checking 3G connections? – Vanwinkle

You using a BOOL, but if I copy your solution, the BOOL will always be false untill if I initialize it as True. Even when the BOOL is initialize before the notification come. – Epaulet

and don't forget to release internetReachable and hostReachable in your dealloc or viewWillDisappear or similar method – Taboret

Note... For approach 1, you'll need to add the "SystemConfiguration framework to the project", or you'll get errors like "_SCError, referenced from":", as detailed here: https://mcmap.net/q/46289/-strange-errors-in-apple-39-s-reachability-files – Marshy

Oh, btw you need to add SystemConfiguration.framework to the project as well (for method 1). – Dotation

Use www.appleiphonecell.com instead of google.com - this url was created by apple for precisely this reason. – Jungjungfrau

What types of things are you all using to "Update the UI on the main thread" asynchronously in Method 1#4? NSNotificationCenter? – Vicennial

Where to call testInternetConnection: or how many times to call it. I'm assuming only once? – Vicennial

I used the Method 1 and trying to switch the Wifi on mac to check the status, strange is when wife disconnected unreachability block is called however' when Wifi made ON' the reachable block gets called , immediately the unreachable block calls as well. Why this error. – Amritsar

Use of www.appleiphonecell.com is now (2018) a bad choice. It now redirects to Apple.com which is a > 40kB html file. Back to google.com - it is only 11kB. BTW google.com/m is same size but is reported to be slower by 120 msec. – Hatcher

I tested your reachability.whenReachable = { reachability in Swift suggestion but it didn't do anything. Instead I'm now using if reachability.connection != .none(Swift 5, latest version of the file) and it's working well (only tested with emulator and wired internet). – Razz

@Keselme I don't know if it answer precisely to your problem, but I use that for now, and it works for me : https://mcmap.net/q/46290/-ios-how-to-test-internet-connection-in-the-most-easy-way-without-freezing-the-app-without-reachability – Modernism

Answer 2

I like to keep things simple. The way I do this is:

//Class.h
#import "Reachability.h"
#import <SystemConfiguration/SystemConfiguration.h>

- (BOOL)connected;

//Class.m
- (BOOL)connected
{
    Reachability *reachability = [Reachability reachabilityForInternetConnection];
    NetworkStatus networkStatus = [reachability currentReachabilityStatus];
    return networkStatus != NotReachable;
}

Then, I use this whenever I want to see if I have a connection:

if (![self connected]) {
    // Not connected
} else {
    // Connected. Do some Internet stuff
}

This method doesn't wait for changed network statuses in order to do stuff. It just tests the status when you ask it to.

Vicegerent

For those who just copy and paste like i did with the above code. Also add SystemConfiguration.framework manually or you will get linking error. – Oniskey

Always come as reachable if i connect with WiFi. WiFi doesn't mean that it is having internet connection. I wanna verify internet connection even it has WiFi connectivity. Can you please help me out? – Brazenfaced

Answer 3

Using Apple's Reachability code, I created a function that'll check this correctly without you having to include any classes.

Include the SystemConfiguration.framework in your project.

Make some imports:

#import <sys/socket.h>
#import <netinet/in.h>
#import <SystemConfiguration/SystemConfiguration.h>

Now just call this function:

/*
Connectivity testing code pulled from Apple's Reachability Example: https://developer.apple.com/library/content/samplecode/Reachability
 */
+(BOOL)hasConnectivity {
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr*)&zeroAddress);
    if (reachability != NULL) {
        //NetworkStatus retVal = NotReachable;
        SCNetworkReachabilityFlags flags;
        if (SCNetworkReachabilityGetFlags(reachability, &flags)) {
            if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)
            {
                // If target host is not reachable
                return NO;
            }

            if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)
            {
                // If target host is reachable and no connection is required
                //  then we'll assume (for now) that your on Wi-Fi
                return YES;
            }


            if ((((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) ||
                 (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0))
            {
                // ... and the connection is on-demand (or on-traffic) if the
                //     calling application is using the CFSocketStream or higher APIs.

                if ((flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0)
                {
                    // ... and no [user] intervention is needed
                    return YES;
                }
            }

            if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN)
            {
                // ... but WWAN connections are OK if the calling application
                //     is using the CFNetwork (CFSocketStream?) APIs.
                return YES;
            }
        }
    }

    return NO;
}

And it's iOS 5 tested for you.

Ray

@JezenThomas This doesn't perform the internet check asynchronously, which is why it is "much slimmer"... You should always be doing this asynchronously by subscribing to notifications so that you don't hang up the app on this process. – Bombazine

This leaks memory - the 'readability' structure (object, thing) needs to be freed with CFRelease(). – Chondrite

Answer 4

This used to be the correct answer, but it is now outdated as you should subscribe to notifications for reachability instead. This method checks synchronously:

---

You can use Apple's Reachability class. It will also allow you to check if Wi-Fi is enabled:

Reachability* reachability = [Reachability sharedReachability];
[reachability setHostName:@"www.example.com"];    // Set your host name here
NetworkStatus remoteHostStatus = [reachability remoteHostStatus];

if (remoteHostStatus == NotReachable) { }
else if (remoteHostStatus == ReachableViaWiFiNetwork) { }
else if (remoteHostStatus == ReachableViaCarrierDataNetwork) { }

The Reachability class is not shipped with the SDK, but rather a part of this Apple sample application. Just download it, and copy Reachability.h/m to your project. Also, you have to add the SystemConfiguration framework to your project.

Vittle

See my comment above about not using Reachability like that. Use it in asynchronous mode and subscribe to the notifications it sends - don't. – Robinet

This code is a good starting point for things that you need to set before you can use the delegate methods for the reachability class. – Biamonte

Answer 5

Here's a very simple answer:

NSURL *scriptUrl = [NSURL URLWithString:@"http://www.google.com/m"];
NSData *data = [NSData dataWithContentsOfURL:scriptUrl];
if (data)
    NSLog(@"Device is connected to the Internet");
else
    NSLog(@"Device is not connected to the Internet");

The URL should point to an extremely small website. I use Google's mobile website here, but if I had a reliable web server I'd upload a small file with just one character in it for maximum speed.

If checking whether the device is somehow connected to the Internet is everything you want to do, I'd definitely recommend using this simple solution. If you need to know how the user is connected, using Reachability is the way to go.

Careful: This will briefly block your thread while it loads the website. In my case, this wasn't a problem, but you should consider this (credits to Brad for pointing this out).

Supernaturalism

I really like this idea, but I would say for the 99.999% reliability while maintaining a small response size, go with www.google.com/m which is the mobile view for google. – Lapel

Apple docs recommend not to do this since it can block the thread on a slow network, can cause app to be terminated in iOS – Brenn

do not use syncronous calls.. as Apple states. (and note that syncronsus call will wrap an asyn call.. :) ) – Selenium

dont use Async code "masked" as async. Doing do you can end up waiting forever (App stuck) if for example DNS are not set.. call will block indefinitely. – Selenium

Answer 6

Here is how I do it in my apps: While a 200 status response code doesn't guarantee anything, it is stable enough for me. This doesn't require as much loading as the NSData answers posted here, as mine just checks the HEAD response.

Swift Code

func checkInternet(flag:Bool, completionHandler:(internet:Bool) -> Void)
{
    UIApplication.sharedApplication().networkActivityIndicatorVisible = true

    let url = NSURL(string: "http://www.google.com/")
    let request = NSMutableURLRequest(URL: url!)

    request.HTTPMethod = "HEAD"
    request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalAndRemoteCacheData
    request.timeoutInterval = 10.0

    NSURLConnection.sendAsynchronousRequest(request, queue:NSOperationQueue.mainQueue(), completionHandler:
    {(response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in

        UIApplication.sharedApplication().networkActivityIndicatorVisible = false

        let rsp = response as! NSHTTPURLResponse?

        completionHandler(internet:rsp?.statusCode == 200)
    })
}

func yourMethod()
{
    self.checkInternet(false, completionHandler:
    {(internet:Bool) -> Void in

        if (internet)
        {
            // "Internet" aka Google URL reachable
        }
        else
        {
            // No "Internet" aka Google URL un-reachable
        }
    })
}

Objective-C Code

typedef void(^connection)(BOOL);

- (void)checkInternet:(connection)block
{
    NSURL *url = [NSURL URLWithString:@"http://www.google.com/"];
    NSMutableURLRequest *headRequest = [NSMutableURLRequest requestWithURL:url];
    headRequest.HTTPMethod = @"HEAD";

    NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration ephemeralSessionConfiguration];
    defaultConfigObject.timeoutIntervalForResource = 10.0;
    defaultConfigObject.requestCachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;

    NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration:defaultConfigObject delegate:self delegateQueue: [NSOperationQueue mainQueue]];

    NSURLSessionDataTask *dataTask = [defaultSession dataTaskWithRequest:headRequest
        completionHandler:^(NSData *data, NSURLResponse *response, NSError *error)
    {
        if (!error && response)
        {
            block([(NSHTTPURLResponse *)response statusCode] == 200);
        }
    }];
    [dataTask resume];
}

- (void)yourMethod
{
    [self checkInternet:^(BOOL internet)
    {
         if (internet)
         {
             // "Internet" aka Google URL reachable
         }
         else
         {
             // No "Internet" aka Google URL un-reachable
         }
    }];
}

Tire

Caution: In my experience, this solution doesn't work all the time. In many cases the response returned is 403, after taking its sweet time. This solution seemed perfect, but doesn't guarantee 100% results. – Tragacanth

As of June 2014, this will fail in mainland China, owing to the Chinese government now completely blocking google.com. (google.cn works, though, but in mainland China, no baidu.com, no internet) Probably better to ping whatever server you need to be communicating with. – Alten

Use www.appleiphonecell.com instead - apple created this url for precisely this reason. – Jungjungfrau

May I suggest an update to your solution, as if there is an error or your block will never be called. (Also, I always check the block for nil, a it will crash if it is) -> BOOL isConnected = NO; if (!error && response) { isConnected = ([(NSHTTPURLResponse *)response statusCode] == 200); } if ( block ) { block(isConnected); } – Rebane

my previous comment was referring to the ObjectiveC solution – Rebane

Answer 7

Apple supplies sample code to check for different types of network availability. Alternatively there is an example in the iPhone developers cookbook.

Note: Please see @KHG's comment on this answer regarding the use of Apple's reachability code.

Dynast

Thanks. I discovered that the Xcode documentation in 3.0 also contains the source code, found by searching for "reachability" in the documentation. – Biamonte

Note that the new revision (09-08-09) of the Reachability sample code from Apple is asynchronous. – Perverse

The links are dead – Concavity

Answer 8

You could use Reachability by  (available here).

#import "Reachability.h"

- (BOOL)networkConnection {
    return [[Reachability reachabilityWithHostName:@"www.google.com"] currentReachabilityStatus];
}

if ([self networkConnection] == NotReachable) { /* No Network */ } else { /* Network */ } //Use ReachableViaWiFi / ReachableViaWWAN to get the type of connection.

Pruett

@Supertecnoboff No, it's async. – Pruett

Answer 9

Apple provides a sample app which does exactly this:

Reachability

Griff

You should note that the Reachability sample only detects which interfaces are active, but not which ones have a valid connection to the internet. Applications should gracefully handle failure even when Reachability reports that everything is ready to go. – Pointing

Happily the situation is a lot better in 3.0, as the system will present a login page for users behind a locked down WiFi where you have to login to use... you use to have to check for the redirect manually (and you still do if developing 2.2.1 apps) – Robinet

I wouldn't say that the Reachability app does exactly what the is asked for. However it's a good starting point for adding the kind of functionality that is asked for, – Hanford

Broken link!, would appreciate if this can be checked/fixed, many thanks – Megalopolis

Answer 10

When using iOS 12 or macOS v10.14 (Mojave) or newer, you can use NWPathMonitor instead of the pre-historic Reachability class. As a bonus you can easily detect the current network connection type:

import Network // Put this on top of your class

let monitor = NWPathMonitor()

monitor.pathUpdateHandler = { path in
    if path.status != .satisfied {
        // Not connected
    }
    else if path.usesInterfaceType(.cellular) {
        // Cellular 3/4/5g connection
    }
    else if path.usesInterfaceType(.wifi) {
        // Wi-Fi connection
    }
    else if path.usesInterfaceType(.wiredEthernet) {
        // Ethernet connection
    }
}

monitor.start(queue: DispatchQueue.global(qos: .background))

More info here: https://developer.apple.com/documentation/network/nwpathmonitor

Oppenheimer

This should be set as the correct answer now since Apple has replaced Reachability with NWPathMonitor. – Sylvester

Is this the way to check for an internet connection? What if I’am on a Local network connected by wifi; then I do have WIFI, but when the wan modem/router has no connection, I still don’t have an Internet connection. – Cecilla

Anyone knows what is path.usesInterfaceType(.loopback)? – Shortbread

@Shortbread apple.stackexchange.com/questions/307759/… – Oppenheimer

this also has energy impact at 80% – Leith

Answer 11

Only the Reachability class has been updated. You can now use:

Reachability* reachability = [Reachability reachabilityWithHostName:@"www.apple.com"];
NetworkStatus remoteHostStatus = [reachability currentReachabilityStatus];

if (remoteHostStatus == NotReachable) { NSLog(@"not reachable");}
else if (remoteHostStatus == ReachableViaWWAN) { NSLog(@"reachable via wwan");}
else if (remoteHostStatus == ReachableViaWiFi) { NSLog(@"reachable via wifi");}

Mulberry

Unless something changed since 4.0 was released, that code is not asynchronous and you are guaranteed to see it show up in Crash Reports - happened to me before. – Ionogen

Answer 12

If you're using AFNetworking you can use its own implementation for internet reachability status.

The best way to use AFNetworking is to subclass the AFHTTPClient class and use this class to do your network connections.

One of the advantages of using this approach is that you can use blocks to set the desired behavior when the reachability status changes. Supposing that I've created a singleton subclass of AFHTTPClient (as said on the "Subclassing notes" on AFNetworking docs) named BKHTTPClient, I'd do something like:

BKHTTPClient *httpClient = [BKHTTPClient sharedClient];
[httpClient setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status)
{
    if (status == AFNetworkReachabilityStatusNotReachable) 
    {
    // Not reachable
    }
    else
    {
        // Reachable
    }
}];

You could also check for Wi-Fi or WLAN connections specifically using the AFNetworkReachabilityStatusReachableViaWWAN and AFNetworkReachabilityStatusReachableViaWiFi enums (more here).

Cassandra

Answer 13

Very simple.... Try these steps:

Step 1: Add the SystemConfiguration framework into your project.

---

Step 2: Import the following code into your header file.

#import <SystemConfiguration/SystemConfiguration.h>

---

Step 3: Use the following method

• Type 1:

  - (BOOL) currentNetworkStatus {
      [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
      BOOL connected;
      BOOL isConnected;
      const char *host = "www.apple.com";
      SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL, host);
      SCNetworkReachabilityFlags flags;
      connected = SCNetworkReachabilityGetFlags(reachability, &flags);
      isConnected = NO;
      isConnected = connected && (flags & kSCNetworkFlagsReachable) && !(flags & kSCNetworkFlagsConnectionRequired);
      CFRelease(reachability);
      return isConnected;
  }
  

---

• Type 2:

  Import header : #import "Reachability.h"

  - (BOOL)currentNetworkStatus
  {
      Reachability *reachability = [Reachability reachabilityForInternetConnection];
      NetworkStatus networkStatus = [reachability currentReachabilityStatus];
      return networkStatus != NotReachable;
  }
  

---

Step 4: How to use:

- (void)CheckInternet
{
    BOOL network = [self currentNetworkStatus];
    if (network)
    {
        NSLog(@"Network Available");
    }
    else
    {
        NSLog(@"No Network Available");
    }
}

Gardol

Is type 1 asynchronous? – Pipit

Answer 14

-(void)newtworkType {

 NSArray *subviews = [[[[UIApplication sharedApplication] valueForKey:@"statusBar"] valueForKey:@"foregroundView"]subviews];
NSNumber *dataNetworkItemView = nil;

for (id subview in subviews) {
    if([subview isKindOfClass:[NSClassFromString(@"UIStatusBarDataNetworkItemView") class]]) {
        dataNetworkItemView = subview;
        break;
    }
}


switch ([[dataNetworkItemView valueForKey:@"dataNetworkType"]integerValue]) {
    case 0:
        NSLog(@"No wifi or cellular");
        break;

    case 1:
        NSLog(@"2G");
        break;

    case 2:
        NSLog(@"3G");
        break;

    case 3:
        NSLog(@"4G");
        break;

    case 4:
        NSLog(@"LTE");
        break;

    case 5:
        NSLog(@"Wifi");
        break;


    default:
        break;
}
}

Shrew

Even if the device is connected to Wifi or some other network type, the internet connection can still be unavailable. Simple test: connect to your home wifi and then unplug your cable modem. Still connected to wifi, but zero internet. – Bombazine

An explanation would be in order. E.g., what is the idea/gist? Please respond by editing (changing) your answer, not here in comments (without "Edit:", "Update:", or similar - the answer should appear as if it was written today). – Alake

Answer 15

- (void)viewWillAppear:(BOOL)animated
{
    NSString *URL = [NSString stringWithContentsOfURL:[NSURL URLWithString:@"http://www.google.com"]];

    return (URL != NULL ) ? YES : NO;
}

Or use the Reachability class.

There are two ways to check Internet availability using the iPhone SDK:

1. Check the Google page is opened or not.

2. Reachability Class

For more information, please refer to Reachability (Apple Developer).

Selfabsorbed

There are two way to check internet availbility in iPhone SDK 1)Check the Google page is opened or not. – Selfabsorbed

-1 : This is a synchronous method that will block the main thread (the one that the app UI is changed on) while it tries to connect to google.com. If your user is on a very slow data connection, the phone will act like the process is unresponsive. – Bombazine

Answer 16

First: Add CFNetwork.framework in framework

Code: ViewController.m

#import "Reachability.h"

- (void)viewWillAppear:(BOOL)animated
{
    Reachability *r = [Reachability reachabilityWithHostName:@"www.google.com"];
    NetworkStatus internetStatus = [r currentReachabilityStatus];

    if ((internetStatus != ReachableViaWiFi) && (internetStatus != ReachableViaWWAN))
    {
        /// Create an alert if connection doesn't work
        UIAlertView *myAlert = [[UIAlertView alloc]initWithTitle:@"No Internet Connection"   message:NSLocalizedString(@"InternetMessage", nil)delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
        [myAlert show];
        [myAlert release];
    }
    else
    {
         NSLog(@"INTERNET IS CONNECT");
    }
}

Coucher

Answer 17

Swift 3 / Swift 4

You must first import

import SystemConfiguration

You can check the Internet connection with the following method:

func isConnectedToNetwork() -> Bool {

    var zeroAddress = sockaddr_in()
    zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
    zeroAddress.sin_family = sa_family_t(AF_INET)

    let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
        $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
            SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
        }
    }

    var flags = SCNetworkReachabilityFlags()
    if !SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) {
        return false
    }
    let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
    let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
    return (isReachable && !needsConnection)
}

Haihaida

energy impact at 80% – Leith

Answer 18

For my iOS projects, I recommend using

Reachability Class

Declared in Swift. For me, it works simply fine with

Wi-Fi and Cellular data

import SystemConfiguration

public class Reachability {

    class func isConnectedToNetwork() -> Bool {

        var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

        let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
                SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
            }
        }

        var flags: SCNetworkReachabilityFlags = SCNetworkReachabilityFlags(rawValue: 0)
        if SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) == false {
            return false
        }

        let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
        let ret = (isReachable && !needsConnection)
        return ret
    }
}

Use a conditional statement,

if Reachability.isConnectedToNetwork() {
    // Enter your code here
}
}
else {
    print("NO Internet connection")
}

This class is useful in almost every case your app uses the Internet connection. Such as if the condition is true, API can be called or task could be performed.

Frazil

"Inspired" by Devang Tandel's answer? – Alake

Answer 19

1. Download the Reachability file, https://gist.github.com/darkseed/1182373

2. And add CFNetwork.framework and 'SystemConfiguration.framework' in framework

3. Do #import "Reachability.h"

First: Add CFNetwork.framework in framework

Code: ViewController.m

- (void)viewWillAppear:(BOOL)animated
{
    Reachability *r = [Reachability reachabilityWithHostName:@"www.google.com"];
    NetworkStatus internetStatus = [r currentReachabilityStatus];

    if ((internetStatus != ReachableViaWiFi) && (internetStatus != ReachableViaWWAN))
    {
        /// Create an alert if connection doesn't work
        UIAlertView *myAlert = [[UIAlertView alloc]initWithTitle:@"No Internet Connection"   message:NSLocalizedString(@"InternetMessage", nil)delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
        [myAlert show];
        [myAlert release];
    }
    else
    {
         NSLog(@"INTERNET IS CONNECT");
    }
}

Epaminondas

Answer 20

First download the reachability class and put reachability.h and reachabilty.m file in your Xcode.

The best way is to make a common Functions class (NSObject) so that you can use it any class. These are two methods for a network connection reachability check:

+(BOOL) reachabiltyCheck
{
    NSLog(@"reachabiltyCheck");
    BOOL status =YES;
    [[NSNotificationCenter defaultCenter] addObserver:self
                                          selector:@selector(reachabilityChanged:)
                                          name:kReachabilityChangedNotification
                                          object:nil];
    Reachability * reach = [Reachability reachabilityForInternetConnection];
    NSLog(@"status : %d",[reach currentReachabilityStatus]);
    if([reach currentReachabilityStatus]==0)
    {
        status = NO;
        NSLog(@"network not connected");
    }
    reach.reachableBlock = ^(Reachability * reachability)
    {
        dispatch_async(dispatch_get_main_queue(), ^{
        });
    };
    reach.unreachableBlock = ^(Reachability * reachability)
    {
        dispatch_async(dispatch_get_main_queue(), ^{
        });
    };
    [reach startNotifier];
    return status;
}

+(BOOL)reachabilityChanged:(NSNotification*)note
{
    BOOL status =YES;
    NSLog(@"reachabilityChanged");
    Reachability * reach = [note object];
    NetworkStatus netStatus = [reach currentReachabilityStatus];
    switch (netStatus)
    {
        case NotReachable:
            {
                status = NO;
                NSLog(@"Not Reachable");
            }
            break;

        default:
            {
                if (!isSyncingReportPulseFlag)
                {
                    status = YES;
                    isSyncingReportPulseFlag = TRUE;
                    [DatabaseHandler checkForFailedReportStatusAndReSync];
                }
            }
            break;
    }
    return status;
}

+ (BOOL) connectedToNetwork
{
    // Create zero addy
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    // Recover reachability flags
    SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress);
    SCNetworkReachabilityFlags flags;
    BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
    CFRelease(defaultRouteReachability);
    if (!didRetrieveFlags)
    {
        NSLog(@"Error. Could not recover network reachability flags");
        return NO;
    }
    BOOL isReachable = flags & kSCNetworkFlagsReachable;
    BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
    BOOL nonWiFi = flags & kSCNetworkReachabilityFlagsTransientConnection;
    NSURL *testURL = [NSURL URLWithString:@"http://www.apple.com/"];
    NSURLRequest *testRequest = [NSURLRequest requestWithURL:testURL  cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:20.0];
    NSURLConnection *testConnection = [[NSURLConnection alloc] initWithRequest:testRequest delegate:self];
    return ((isReachable && !needsConnection) || nonWiFi) ? (testConnection ? YES : NO) : NO;
}

Now you can check network connection in any class by calling this class method.

Reprovable

Answer 21

There is also another method to check Internet connection using the iPhone SDK.

Try to implement the following code for the network connection.

#import <SystemConfiguration/SystemConfiguration.h>
#include <netdb.h>

/**
     Checking for network availability. It returns
     YES if the network is available.
*/
+ (BOOL) connectedToNetwork
{

    // Create zero addy
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    // Recover reachability flags
    SCNetworkReachabilityRef defaultRouteReachability =
        SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr *)&zeroAddress);
    SCNetworkReachabilityFlags flags;

    BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
    CFRelease(defaultRouteReachability);

    if (!didRetrieveFlags)
    {
        printf("Error. Could not recover network reachability flags\n");
        return NO;
    }

    BOOL isReachable = ((flags & kSCNetworkFlagsReachable) != 0);
    BOOL needsConnection = ((flags & kSCNetworkFlagsConnectionRequired) != 0);

    return (isReachable && !needsConnection) ? YES : NO;
}

Atop

Answer 22

To do this yourself is extremely simple. The following method will work. Just be sure to not allow a hostname protocol such as HTTP, HTTPS, etc. to be passed in with the name.

-(BOOL)hasInternetConnection:(NSString*)urlAddress
{
    SCNetworkReachabilityRef ref = SCNetworkReachabilityCreateWithName(kCFAllocatorDefault, [urlAddress UTF8String]);
    SCNetworkReachabilityFlags flags;
    if (!SCNetworkReachabilityGetFlags(ref, &flags))
    {
        return NO;
    }
    return flags & kSCNetworkReachabilityFlagsReachable;
}

It is quick simple and painless.

Assuage

Answer 23

I think this one is the best answer.

"Yes" means connected. "No" means disconnected.

#import "Reachability.h"

 - (BOOL)canAccessInternet
{
    Reachability *IsReachable = [Reachability reachabilityForInternetConnection];
    NetworkStatus internetStats = [IsReachable currentReachabilityStatus];

    if (internetStats == NotReachable)
    {
        return NO;
    }
    else
    {
        return YES;
    }
}

Penology

Answer 24

The Reachability class is OK to find out if the Internet connection is available to a device or not...

But in case of accessing an intranet resource:

Pinging the intranet server with the reachability class always returns true.

So a quick solution in this scenario would be to create a web method called pingme along with other webmethods on the service. The pingme should return something.

So I wrote the following method on common functions

-(BOOL)PingServiceServer
{
    NSURL *url=[NSURL URLWithString:@"http://www.serveraddress/service.asmx/Ping"];

    NSMutableURLRequest *urlReq=[NSMutableURLRequest requestWithURL:url];

    [urlReq setTimeoutInterval:10];

    NSURLResponse *response;

    NSError *error = nil;

    NSData *receivedData = [NSURLConnection sendSynchronousRequest:urlReq
                                                 returningResponse:&response
                                                             error:&error];
    NSLog(@"receivedData:%@",receivedData);

    if (receivedData !=nil)
    {
        return YES;
    }
    else
    {
        NSLog(@"Data is null");
        return NO;
    }
}

The above method was so useful for me, so whenever I try to send some data to the server I always check the reachability of my intranet resource using this low timeout URLRequest.

Synchrotron

Answer 25

Import Reachable.h class in your ViewController, and use the following code to check connectivity:

#define hasInternetConnection [[Reachability reachabilityForInternetConnection] isReachable]
if (hasInternetConnection){
      // To-do block
}

Moyer

Doesn't work if you are connected to a WiFi without internet. – Obstructionist

Answer 26

• Step 1: Add the Reachability class in your Project.
• Step 2: Import the Reachability class

• Step 3: Create the below function

  - (BOOL)checkNetConnection {
      self.internetReachability = [Reachability reachabilityForInternetConnection];
      [self.internetReachability startNotifier];
      NetworkStatus netStatus = [self.internetReachability currentReachabilityStatus];
      switch (netStatus) {
          case NotReachable:
          {
              return NO;
          }
  
          case ReachableViaWWAN:
          {
               return YES;
          }
  
          case ReachableViaWiFi:
          {
               return YES;
          }
      }
  }
  

• Step 4: Call the function as below:

  if (![self checkNetConnection]) {
      [GlobalFunctions showAlert:@""
                       message:@"Please connect to the Internet!"
                       canBtntitle:nil
                       otherBtnTitle:@"Ok"];
      return;
  }
  else
  {
      Log.v("internet is connected","ok");
  }
  

Mehta

Apple's docs state this Note: Reachability cannot tell your application if you can connect to a particular host, only that an interface is available that might allow a connection, and whether that interface is the WWAN. – Immuno

Answer 27

Checking the Internet connection availability in (iOS) Xcode 8 , Swift 3.0

This is simple method for checking the network availability like our device is connected to any network or not. I have managed to translate it to Swift 3.0 and here the final code. The existing Apple Reachability class and other third party libraries seemed to be too complicated to translate to Swift.

This works for both 3G,4G and WiFi connections.

Don’t forget to add “SystemConfiguration.framework” to your project builder.

//Create new swift class file Reachability in your project.
import SystemConfiguration
public class InternetReachability {

class func isConnectedToNetwork() -> Bool {
   var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
   zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
   zeroAddress.sin_family = sa_family_t(AF_INET)
   let defaultRouteReachability = withUnsafePointer(&zeroAddress) {
          SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0)).takeRetainedValue()
   }
   var flags: SCNetworkReachabilityFlags = 0
   if SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) == 0 {
          return false
   }
   let isReachable = (flags & UInt32(kSCNetworkFlagsReachable)) != 0
   let needsConnection = (flags & UInt32(kSCNetworkFlagsConnectionRequired)) != 0

   return isReachable && !needsConnection
  }
}

// Check network connectivity from anywhere in project by using this code.
 if InternetReachability.isConnectedToNetwork() == true {
         print("Internet connection OK")
  } else {
         print("Internet connection FAILED")
  }

Varitype

MacOS version? Otherwise main question is NOT answered! – Schoolgirl

Please check main answer heading. – Varitype

Answer 28

Swift 5 and later:

public class Reachability {
    class func isConnectedToNetwork() -> Bool {
        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
        zeroAddress.sin_family = sa_family_t(AF_INET)

        guard let defaultRouteReachability = withUnsafePointer(to: &zeroAddress, {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                SCNetworkReachabilityCreateWithAddress(nil, $0)
            }
        }) else {
            return false
        }

        var flags: SCNetworkReachabilityFlags = []
        if !SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) {
            return false
        }

        let isReachable = flags.contains(.reachable)
        let needsConnection = flags.contains(.connectionRequired)

        return (isReachable && !needsConnection)
    }

Call this class like this:

if Reachability.isConnectedToNetwork() == true {
    // Do something
} else {
    // Do something
}

Maley

energy impact at 80% ..... – Leith

Answer 29

Get the Reachabilty class from https://github.com/tonymillion/Reachability, add the system configuration framework in your project, do import Reachability.h in your class and implement the custom methods as below:

- (BOOL)isConnectedToInternet
{
    //return NO; // Force for offline testing
    Reachability *hostReach = [Reachability reachabilityForInternetConnection];
    NetworkStatus netStatus = [hostReach currentReachabilityStatus];
    return !(netStatus == NotReachable);
}

Beseem

-1; adds nothing to this thread that the accepted answer doesn't already cover better, IMO. Also, your entire method body can just be replaced with return [[Reachability reachabilityForInternetConnection] isReachable]; – Erlin

Answer 30

import "Reachability.h"

-(BOOL)netStat
{
    Reachability *test = [Reachability reachabilityForInternetConnection];
    return [test isReachable];
}

Zoara

Answer 31

Create an object of AFNetworkReachabilityManager and use the following code to track the network connectivity

self.reachabilityManager = [AFNetworkReachabilityManager managerForDomain:@"yourDomain"];
[self.reachabilityManager startMonitoring];
[self.reachabilityManager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
        switch (status) {
            case AFNetworkReachabilityStatusReachableViaWWAN:
            case AFNetworkReachabilityStatusReachableViaWiFi:
                break;
            case AFNetworkReachabilityStatusNotReachable:
                break;
            default:
                break;
        }
    }];

Antonantone

Answer 32

Check Internet connection availability in (iOS) using Xcode 9 and Swift 4.0

Follow the below steps

Step 1:

Create an extension file and give it the name ReachabilityManager.swift. Then add the lines of code below.

import Foundation
import SystemConfiguration
public class ConnectionCheck
{
    class func isConnectedToNetwork() -> Bool
    {
        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
        zeroAddress.sin_family = sa_family_t(AF_INET)

        guard let defaultRouteReachability = withUnsafePointer(to: &zeroAddress,
        {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                SCNetworkReachabilityCreateWithAddress(nil, $0)
            }
        })
        else {
            return false
        }

        var flags: SCNetworkReachabilityFlags = []
        if !SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) {
            return false
        }

        let isReachable = flags.contains(.reachable)
        let needsConnection = flags.contains(.connectionRequired)

        return (isReachable && !needsConnection)
    }
}

Step 2: Call the extension above using the code below.

if ConnectionCheck.isConnectedToNetwork()
{
     print("Connected")
     // Online related Business logic
}
else{
     print("disConnected")
     // Offline related business logic
}

Monarch

Answer 33

This is for Swift 3.0 and async. Most answers are sync solution which is going to block your main thread if you have a very slow connection.

This solution is better, but not perfect because it rely on Google to check the connectivity, so feel free to use another URL.

func checkInternetConnection(completionHandler:@escaping (Bool) -> Void)
{
    if let url = URL(string: "http://www.google.com/")
    {
        var request = URLRequest(url: url)
        request.httpMethod = "HEAD"
        request.cachePolicy = .reloadIgnoringLocalAndRemoteCacheData
        request.timeoutInterval = 5

        let tast = URLSession.shared.dataTask(with: request, completionHandler:
        {
            (data, response, error) in

            completionHandler(error == nil)
        })
        tast.resume()
    }
    else
    {
        completionHandler(true)
    }
}

Summerly

Answer 34

Pod `Alamofire` has `NetworkReachabilityManager`, you just have to create one function 

func isConnectedToInternet() ->Bool {
        return NetworkReachabilityManager()!.isReachable
}

Fantastically

Answer 35

Alamofire

I know the question is asking for Coca Touch solution, but I want to provide a solution for people who searched check the Internet connection on iOS and will have one more option here.

If you are already using Alamofire, here is what you can benefit from that.

You can add following class to your app, and call MNNetworkUtils.main.isConnected() to get a Boolean value on whether it’s connected or not.

#import Alamofire

class MNNetworkUtils {
  static let main = MNNetworkUtils()
  init() {
    manager = NetworkReachabilityManager(host: "google.com")
    listenForReachability()
  }

  private let manager: NetworkReachabilityManager?
  private var reachable: Bool = false
  private func listenForReachability() {
    self.manager?.listener = { [unowned self] status in
      switch status {
      case .notReachable:
        self.reachable = false
      case .reachable(_), .unknown:
        self.reachable = true
      }
    }
    self.manager?.startListening()
  }

  func isConnected() -> Bool {
    return reachable
  }
}

This is a singleton class. Every time, when the user connects or disconnects the network, it will override self.reachable to true/false correctly, because we start listening for the NetworkReachabilityManager on singleton initialization.

Also in order to monitor reachability, you need to provide a host. Currently, I am using google.com, but feel free to change to any other hosts or one of yours if needed. Change the class name and file name to anything matching your project.

Ovotestis

Answer 36

Please try this. It will help you (Swift 4)

1. Install Reachability via CocoaPods or Carthage: Reachability

2. Import Reachability and use it in the Network class

   import Reachability
   
   class Network {
   
      private let internetReachability : Reachability?
      var isReachable : Bool = false
   
      init() {
   
          self.internetReachability = Reachability.init()
          do{
              try self.internetReachability?.startNotifier()
              NotificationCenter.default.addObserver(self, selector: #selector(self.handleNetworkChange), name: .reachabilityChanged, object: internetReachability)
          }
          catch {
           print("could not start reachability notifier")
          }
      }
   
      @objc private func handleNetworkChange(notify: Notification) {
   
          let reachability = notify.object as! Reachability
          if reachability.connection != .none {
              self.isReachable = true
          }
          else {
              self.isReachable = false
          }
          print("Internet Connected : \(self.isReachable)") //Print Status of Network Connection
      }
   }
   

3. Use like the below where you need it.

   var networkOBJ = Network()
   // Use "networkOBJ.isReachable" for Network Status
   print(networkOBJ.isReachable)
   

Darden

Answer 37

//
//  Connectivity.swift
// 
//
//  Created by Kausik Jati on 17/07/20.
// 
//

import Foundation
import Network

enum ConnectionState: String {
    case notConnected = "Internet connection not avalable"
    case connected = "Internet connection avalable"
    case slowConnection = "Internet connection poor"
}
protocol ConnectivityDelegate: class {
    func checkInternetConnection(_ state: ConnectionState, isLowDataMode: Bool)
}
class Connectivity: NSObject {
    private let monitor = NWPathMonitor()
    weak var delegate: ConnectivityDelegate? = nil
    private let queue = DispatchQueue.global(qos: .background)
    private var isLowDataMode = false
    static let instance = Connectivity()
private override init() {
    super.init()
    monitor.start(queue: queue)
    startMonitorNetwork()
}
private func startMonitorNetwork() {
    monitor.pathUpdateHandler = { path in
        if #available(iOS 13.0, *) {
            self.isLowDataMode = path.isConstrained
        } else {
            // Fallback on earlier versions
            self.isLowDataMode = false
        }
        
        if path.status == .requiresConnection {
            print("requiresConnection")
                self.delegate?.checkInternetConnection(.slowConnection, isLowDataMode: self.isLowDataMode)
        } else if path.status == .satisfied {
            print("satisfied")
                 self.delegate?.checkInternetConnection(.connected, isLowDataMode: self.isLowDataMode)
        } else if path.status == .unsatisfied {
            print("unsatisfied")
                self.delegate?.checkInternetConnection(.notConnected, isLowDataMode: self.isLowDataMode)
            }
        }
    
    }
    func stopMonitorNetwork() {
        monitor.cancel()
    }
}

Corie

please add description as well – Menarche

Connectivity.instance.delegate = self extension ViewController: ConnectivityDelegate { func checkInternetConnection(_ state: ConnectionState, isLowDataMode: Bool) { } } – Corie

Answer 38

Swift 5, Alamofire, host

// Session reference
var alamofireSessionManager: Session!

func checkHostReachable(completionHandler: @escaping (_ isReachable:Bool) -> Void) {
    let configuration = URLSessionConfiguration.default
    configuration.timeoutIntervalForRequest = 1
    configuration.timeoutIntervalForResource = 1
    configuration.requestCachePolicy = .reloadIgnoringLocalCacheData

    alamofireSessionManager = Session(configuration: configuration)

    alamofireSessionManager.request("https://google.com").response { response in
        completionHandler(response.response?.statusCode == 200)
    }
}

// Using
checkHostReachable() { (isReachable) in
    print("isReachable:\(isReachable)")
}

Ilyse

Answer 39

Try this:

- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error


if ([self.delegate respondsToSelector:@selector(getErrorResponse:)]) {
    [self.delegate performSelector:@selector(getErrorResponse:) withObject:@"No Network Connection"];
}

UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"BMC" message:@"No Network Connection" delegate:self cancelButtonTitle:nil otherButtonTitles:@"OK",nil];
[alertView show];

}

Mohammadmohammed

At minimum add an explanation what this code does and how it solves the problem. – Deformed