Check for internet connection availability in Swift

Question

Is there a way to check if the internet connection is available using Swift?

I know there are many third party libraries to do this but they are all written in Objective-C. I'm looking for a Swift alternative.

Copyboy

One of Swift's huge benefits is that it integrates well with Objective-C (and libraries of such). – Halide

Indeed. What problems are you having using one of the existing libraries? It's pretty simple to use an Objective C library from Swift, and it's going to prove extremely difficult for you to write any kind of app in Swift if you can't do it. – Obsequies

@MattGibson almost everything you can do in ObjC can be done in Swift with relative ease. Granted, in this case there would be a few extra lines but still far from "extremely difficult" – Weightless

@ByronCoetsee I was including using libraries like AppKit, etc.—my point is that you'll need to know how to interact with Objective C libraries in order to write anything useful in Swift. – Obsequies

See alamofire answer - https://mcmap.net/q/48297/-check-for-internet-connection-with-swift – Troxler

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

Answer 1

As mentioned in the comments, although its possible to use Objective-C libraries in Swift, I wanted a more pure Swift solution. The existing Apple Reachability class and other third party libraries seemed to be too complicated for me to translate to Swift. I Googled some more and I came across this article which shows a simple method to check for network availability. I set out to translate this to Swift. I hit many snags but thanks to Martin R from StackOverflow, I managed to resolve them and finally get a workable solution in Swift. Here is the code.

import Foundation
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(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
    }

}

For Swift > 3.0

public class Reachability {
    public 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
        }
        if flags.isEmpty {
            return false
        }

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

        return (isReachable && !needsConnection)
    }
}

This works for both 3G and WiFi connections. I've also uploaded it to my GitHub with a working example.

Copyboy

Please can you consider releasing this code under a less restrictive licence? Especially seeing as the original code which it is based upon seems to have been released without any licence. – Subzero

Oh sure. What would you suggest to be the suitable one? – Copyboy

Thanks for the swift response (no pun intended). MIT or Apache would be ideal - thanks! – Subzero

Done. Changed it to MIT. – Copyboy

Hello Isuru, I found a much simplier looking code, but maybe not as good as yours: What do you think about that: ios8programminginswift.wordpress.com/2014/08/17/… – Photoluminescence

@Photoluminescence I've seen that post too. I even tried it myself but the code simply didn't work. I got a few compiler errors saying there is no type called Reachability which is understandable because SystemConfiguration framework doesn't support this functionality out of the box as far as I know. Did it work for you? I left a comment in that post as well. Guess the user either didn't approve it or removed it. – Copyboy

@Isuru: Thank you very much for your answer and sorry, that I consumed your time with that link to a code, that of course does not work. It is just, I was so impressed by the complexity of your code, since I don't understand really what is happening in your class Reachability, but I can confirm, it works perfectly. But when I was looking for an alternative code, that is less complex and maybe understandable for me, I would have taken that. But as already said, that code is not less complex, it is simple not working ! Sorry again for you time and thanks for your great code! – Photoluminescence

is a way to get notification if user changes network settings, i.e. put device to airplane mode? I need to reload tableView – Joelynn

@János Currently this is impossible to achieve in Swift the way it's done in Objective-C. SCNetworkReachabilitySetCallback expects a pointer to a C function as second parameter, and there is currently no method to pass a Swift function or closure.. Here's the question I asked regarding this. Sorry. – Copyboy

I found an other issue, if 3G is turned on but I have no more data capacity then isConnectedToNetwork returns true, but I can not call my web service – Joelynn

As @Copyboy said, this is based on https://mcmap.net/q/48801/-how-to-use-scnetworkreachability-in-swift, which has now been updated for Swift 2. – Horsefly

@János: Setting a notification callback is now possible with Swift 2, see updated answer https://mcmap.net/q/49177/-working-with-c-apis-from-swift. – Horsefly

swift 2 update :#30740500 – Undertrick

The swift2 update doesn't cover the full code, I'm still receiving errors on the code in Swift2 – Whereunto

@János have you found a solution? – Possibly

I added an answer at the bottom you should look at and update you answer. The c code in your logic up there is broken in swift 2.0. Use the swift structs instead of the objective c enums and you should be good. Happy Coding – Zook

Another issue if you are connected to a public wifi but it takes you to a splash page or require you to 'login' before you can proceed. In this case you are connected but you cannot access the web.I combined the above with a ping to Google. – Fowliang

This code is based on https://mcmap.net/q/48801/-how-to-use-scnetworkreachability-in-swift (essentially a copy of revision 6), which has now been updated for the latest Swift 3 from Xcode 8 beta 6. – Horsefly

@Copyboy This does NOT work when you are connected to 4G network. It returns false – Livvie

is there a way of creating an observer from this? – Thunderbolt

Answer 2

For Swift 3.1 (iOS 10.1)

If you want to make the distinction between the network-type (i.e. WiFi or WWAN):

You can use:

func checkWiFi() -> Bool {

    let networkStatus = Reachability().connectionStatus()
    switch networkStatus {
    case .Unknown, .Offline:
        return false
    case .Online(.WWAN):
        print("Connected via WWAN")
        return true
    case .Online(.WiFi):
        print("Connected via WiFi")
        return true
    }
}

Here is the entire Reachability-Class that distinguished between network-types:

import Foundation
import SystemConfiguration

import UIKit
import SystemConfiguration.CaptiveNetwork

public let ReachabilityStatusChangedNotification = "ReachabilityStatusChangedNotification"

public enum ReachabilityType: CustomStringConvertible {
    case WWAN
    case WiFi

    public var description: String {
        switch self {
        case .WWAN: return "WWAN"
        case .WiFi: return "WiFi"
        }
    }
}

public enum ReachabilityStatus: CustomStringConvertible  {
    case Offline
    case Online(ReachabilityType)
    case Unknown

    public var description: String {
        switch self {
        case .Offline: return "Offline"
        case .Online(let type): return "Online (\(type))"
        case .Unknown: return "Unknown"
        }
    }
}

public class Reachability {

    func connectionStatus() -> ReachabilityStatus {
        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

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

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

        return ReachabilityStatus(reachabilityFlags: flags)
    }

    func monitorReachabilityChanges() {
        let host = "google.com"
        var context = SCNetworkReachabilityContext(version: 0, info: nil, retain: nil, release: nil, copyDescription: nil)
        let reachability = SCNetworkReachabilityCreateWithName(nil, host)!

        SCNetworkReachabilitySetCallback(reachability, { (_, flags, _) in
            let status = ReachabilityStatus(reachabilityFlags: flags)

            NotificationCenter.default.post(name: NSNotification.Name(rawValue: ReachabilityStatusChangedNotification), object: nil, userInfo: ["Status": status.description])}, &context)

        SCNetworkReachabilityScheduleWithRunLoop(reachability, CFRunLoopGetMain(), CFRunLoopMode.commonModes.rawValue)
    }
}

extension ReachabilityStatus {

    public init(reachabilityFlags flags: SCNetworkReachabilityFlags) {
        let connectionRequired = flags.contains(.connectionRequired)
        let isReachable = flags.contains(.reachable)
        let isWWAN = flags.contains(.isWWAN)

        if !connectionRequired && isReachable {
            if isWWAN {
                self = .Online(.WWAN)
            } else {
                self = .Online(.WiFi)
            }
        } else {
            self =  .Offline
        }
    }
}

Chimborazo

working well as of Dec 3, 2016, iOS 10 and swift 3.1, thanks! – Linkous

Hello, if we want to differentiate Wifi/3G/Mobile-Data/4G connection for that how we can identify. – Yodle

Answer 3

I give you better way...

You must create a class with this code

 import Foundation
 public class Reachability {

class func isConnectedToNetwork()->Bool{

    var Status:Bool = false
    let url = NSURL(string: "http://google.com/")
    let request = NSMutableURLRequest(URL: url!)
    request.HTTPMethod = "HEAD"
    request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalAndRemoteCacheData
    request.timeoutInterval = 10.0

    var response: NSURLResponse?

    var data = NSURLConnection.sendSynchronousRequest(request, returningResponse: &response, error: nil) as NSData?

    if let httpResponse = response as? NSHTTPURLResponse {
        if httpResponse.statusCode == 200 {
            Status = true
        }
    }

    return Status
  }
}

And then you can check internet connection anywhere in your project using this code:

if Reachability.isConnectedToNetwork() == true {
     println("Internet connection OK")
} else {
     println("Internet connection FAILED")
}

Very easy!

*This way is based on Vikram Pote answer!

Readymade

Please be aware that you should not use this method over the one used above. In applications which require constant connectivity, a response check like this method will result in the app hanging in situations where your internet connectivity is poor (i.e. on Edge/GPRS). Please don't use this solution!! – Leuko

Bad way 1) Need extra hit to server evry time 2) google.com can also be down – Harriet

1. Yes, this way need extra hit to server every time, but it gives a 100% guarantee that the Internet is available... there are times when the device is connected to a wifi network but does not provide internet access! In this situation, this way determines the lack of access to the Internet ... other ways - no! 2. You can use your own server instead google.com ... This was originally meant ... – Readymade

poor solution, connection killer. – Doggo

gokhanakkurt, please, suggest another solution that ensures that the Internet works at 100% – Readymade

call an url to check if there is a connection is bad practice. – Mansuetude

You assume google.com web-server is some kind of nature force, that is always available? what kind of technical assumption is this? Also this harasses a specific server which is bad practice. Last, this test will take longer than other methods, because it depends on the response-times of Google servers, not the actual network. It is usually preferable to go a far as your ISP - and no more - to verify "internet" availability. For "Network" availability, even closer - no farther than the nearest router. – Kerman

Answer 4

SWIFT 3: Checks for wifi and internet connection:

import Foundation
import SystemConfiguration

public class Reachability {
    public 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)
    }
}

USAGE:

if Reachability.isConnectedToNetwork() == true {
    print("Connected to the internet")
    //  Do something
} else {
    print("No internet connection")
    //  Do something
}

Darbee

public func isConnectedToNetwork() {...} should be changed to class func isConnectedToNetwork{...} for your usage case. – Grof

Answer 5

Since sendSynchronousRequest is deprecated, I tried this but 'return Status' was called before the response had finished.

This answer works well though, Check for internet connection with Swift

Here's what I tried anyway:

import Foundation

public class Reachability {

    class func isConnectedToNetwork()->Bool{

        var Status:Bool = false
        let url = NSURL(string: "http://google.com/")
        let request = NSMutableURLRequest(URL: url!)
        request.HTTPMethod = "HEAD"
        request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalAndRemoteCacheData
        request.timeoutInterval = 10.0
        let session = NSURLSession.sharedSession()

        session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
            print("data \(data)")
            print("response \(response)")
            print("error \(error)")

            if let httpResponse = response as? NSHTTPURLResponse {
                print("httpResponse.statusCode \(httpResponse.statusCode)")
                if httpResponse.statusCode == 200 {
                    Status = true
                }
            }

        }).resume()


        return Status
    }
}

Aron

I liked and used yours solution. But i added a combined it with this answer: stackoverflow.com/a/34591379 aka. i added a semaphore.. So i wait for the the task to finish. – Chiffchaff

Answer 6

You can also use below answer.

    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" mean Google
        }
        else
        {
            // No "Internet" no Google
        }
    })
   }

Laodicea

Thanks! I got an auto-correct from response as NSHTTPURLResponse? to response as! NSHTTPURLResponse? in Swift 1.2. – Ampliate

Answer 7

If you just want to know if it's connected or not and you're using SwiftUI:

Service:

import Foundation
import Network

class ConnectionService: ObservableObject {
    @Published var connected: Bool = false
    
    private var monitor: NWPathMonitor
    
    init() {
        monitor = NWPathMonitor()

        monitor.pathUpdateHandler = { [weak self] path in
            switch path.status {
            case .satisfied:
                self?.connected = true
            case .unsatisfied, .requiresConnection:
                self?.connected = false
            @unknown default:
                self?.connected = false
            }
        }

        monitor.start(queue: DispatchQueue.main)
    }
}

Usage:

// step 1: add in your App struct
@StateObject var internet = ConnectionService() 

// step 2: add this modifier to your top level view
.environmentObject(internet) 

// step 3: add this in any child view
@EnvironmentObject var internet: ConnectionService 

// step 4: example usage in that child view
Text("internet: \(internet.connected ? "true" : "false")") 

Exarch

Answer 8

Swift 4

if isInternetAvailable() {
    print("if called Internet Connectivity success \(isInternetAvailable())");
} else {
    print("else called Internet Connectivity success \(isInternetAvailable())");
}

func isInternetAvailable() -> 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.contains(.reachable)
   let needsConnection = flags.contains(.connectionRequired)
   //   print(isReachable && !needsConnection)
   return (isReachable && !needsConnection)
}

Jeffcott

Answer 9

For Swift 5:

import Network
let monitor = NWPathMonitor()

func checkInterwebs() -> Bool {
    var status = false
    monitor.pathUpdateHandler = { path in
        if path.status == .satisfied {
            status = true  // online
        }
    }
    return status
}

Nonesuch

Seems like this won't work as you didn't do monitor.start(queue: someQueue) – Agha

Answer 10

If you use Alamofire in your project you can Use this sample func:

import Alamofire

class Network {

    func isConnected(_ complition: @escaping(Bool) -> Void) {
        let retVal = NetworkReachabilityManager()!.isReachable
        complition(retVal)
    }

}

Igniter

Answer 11

SWIFT 3: Check 3G & Wi-Fi connection

DispatchQueue.main.async {
        let url = URL(string: "https://www.google.com")!
        let request = URLRequest(url: url)

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

            if error != nil {
                // do something here...
                print("Internet Connection not Available!")
            }
            else if let httpResponse = response as? HTTPURLResponse {
                if httpResponse.statusCode == 200 {
                    // do something here...
                    print("Internet Connection OK")
                }
                print("statusCode: \(httpResponse.statusCode)")
            }

        }
        task.resume()
}

Arv

This is not a preferred way. What if at some point of future the provided web link stops to respond or is down. I would recommend to use Apple SystemConfiguration framework for this. See the above answer. – Fleam