Is there any way of asking an iOS view which of its children has first responder status? [duplicate]

Question

In Mac OS X, you can find the first responder like this:

[[self window] firstResponder]

Is there any way of doing it in iOS? Or do you need to enumerate the child controls and send an isFirstRespondermessage to each one?

Micamicaela

Answer 1

You would need to iterate over all of the child controls and test the isFirstResponder property. When you encounter TRUE, break out of the loop.

UIView *firstResponder;
for (UIView *view in self.view.subviews) //: caused error
{
    if (view.isFirstResponder)
    {
        firstResponder = view;
        break;
    }
}

---

BETTER SOLUTION

See Jakob's answer.

Snowblink

This snippet only searches direct descendants of a view, but wont find the first responder when it is nested deeper. – Compound

Answer 2

I really like VJK's solution, but as MattDiPasquale suggests it seems more complex than necessary. So I wrote this simpler version:

Objective-C

UIResponder+FirstResponder.h:

#import <UIKit/UIKit.h>

@interface UIResponder (FirstResponder)
    +(id)currentFirstResponder;
@end

UIResponder+FirstResponder.m:

#import "UIResponder+FirstResponder.h"

static __weak id currentFirstResponder;

@implementation UIResponder (FirstResponder)

+(id)currentFirstResponder {
    currentFirstResponder = nil;
    [[UIApplication sharedApplication] sendAction:@selector(findFirstResponder:) to:nil from:nil forEvent:nil];
    return currentFirstResponder;
}

-(void)findFirstResponder:(id)sender {
   currentFirstResponder = self;
}

@end

Swift 4

import UIKit

extension UIResponder {

    private static weak var _currentFirstResponder: UIResponder?

    static var currentFirstResponder: UIResponder? {
        _currentFirstResponder = nil
        UIApplication.shared.sendAction(#selector(UIResponder.findFirstResponder(_:)), to: nil, from: nil, for: nil)

        return _currentFirstResponder
    }

    @objc func findFirstResponder(_ sender: Any) {
        UIResponder._currentFirstResponder = self
    }
}

I also made it a class method since that seemed to make more sense. You can now find the first responder like so: [UIResponder currentFirstResponder]

---

Compound

This is brilliantly simple, well done. – Kenny

Wouldn't using UIResponder * make more sense than id? – Kenny

@StevenFisher I'm pretty sure that the first responder is always a view, so maybe UIView* would make even more sense. (eg. a view controller would be in the responder chain, but it can't be the first responder -- the first responder would be the view it controls) But to be honest, I didn't think too deeply about the return type. Using id avoids having to use explicit casts. – Compound

instancetype would fit well :) – Shumate

Ok, gonna use this in all of my projects from now on, neat snippet! – Timberhead

@Shumate I think that instancetype is not a good idea here. Imagine calling [UITextView currentFirstResponder], there is no guarantee that the first responder is actually a UITextView. UIResponder * as return value should be fine. – Portion

fwiw: View controllers can become first responders. All you need to do is to return YES from -canBecomeFirstResponder. This is great for input accessory views that are always on screen or handling shortcuts even when no view is focussed, etc. As such, using UIView * would be wrong here. – Epigrammatize

Great solution! I came up with something similar, but instead of using a static variable, I subclassed UIEvent. This makes it safer (e.g. if you have multiple threads, or if you have nested function calls, it'll still work correctly). – Elrod

@Elrod Making +currentFirstResponder reentrant is pointless if you call it only from the main thread. And you really shouldn't call it from a background thread. UIKit is not thread safe. – Compound

wish I could upvote this answer several times. – Chordophone

Here is a Swift implementation: https://mcmap.net/q/76644/-get-the-current-first-responder-without-using-a-private-api – Ul

Doesn't work in UIKeyboardWillShowNotification, since its not firstResponder yet when the notification handler called... – Excess

Doesn't work at least on iOS9. I put focus into TextField which is in the scrollview. After I check firstResponder in the way described and get ScrollView as the first responder. At the same time [[[[UIApplication sharedApplication] windows] firstObject] valueForKey:@"firstResponder"] gives TextField. – Lunkhead

@Lunkhead I have some text fields on a uitableview inside a cell, the method above works even on iOS 9, i haven't tried a scrollview, but since the tableview inherits from scrollview, I think it should also work?. Have you found other instances where this solution doesn't work? – Misogynist

It's won't work at least if responder is UITableViewCell (https://mcmap.net/q/77126/-uitableviewcell-skipped-in-responder-chain). – Allyl

Highly recommended to prefix objc category methods with your class prefix (for ex abc_currentFirstResponder). – Yah

anyone tell me how can i use this code in non ARC project? – Acupuncture

Just a gotcha, if you have custom UIControl's (i.e. a UITextField subclass) and implement override open func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool then ensure you return true for the action this solution uses, i.e. if action == #selector(findFirstResponder(sender:)) {return true} – Fiske

Answer 3

I wrote a category on UIResponder to find the first responder

@interface UIResponder (firstResponder)
- (id) currentFirstResponder;
@end

and

#import <objc/runtime.h>
#import "UIResponder+firstResponder.h"

static char const * const aKey = "first";

@implementation UIResponder (firstResponder)

- (id) currentFirstResponder {
    [[UIApplication sharedApplication] sendAction:@selector(findFirstResponder:) to:nil from:self forEvent:nil];
    id obj = objc_getAssociatedObject (self, aKey);
    objc_setAssociatedObject (self, aKey, nil, OBJC_ASSOCIATION_ASSIGN);
    return obj;
}

- (void) setCurrentFirstResponder:(id) aResponder {
    objc_setAssociatedObject (self, aKey, aResponder, OBJC_ASSOCIATION_ASSIGN);
}

- (void) findFirstResponder:(id) sender {
    [sender setCurrentFirstResponder:self];
}

@end

Then in any class that derives from a UIResponder you can get the first responder by calling

UIResponder* aFirstResponder = [self currentFirstResponder];

but remember to import the UIResponder category interface file first!

This uses documented API's so there should be no app store rejection issues.

Steeple

Using -[UIApplication sendAction:to:from:forEvent:] is neat! :) But, instead of using an associated object to reference firstResponder, why not just use a static variable since there'll only be one firstResponder at a time? – Maryjanemaryjo

Oh that's clever! I couldn't make send of your sendAction: until I read the docs. That must be the only part of iOS's APIs that actually gives direct access to the first responder. – Thaxton

just returns the view that asked the currentFirstResponder. When i check the responder if it's first responder as expected it say no – Triad

I know this is old, and there is an accepted (and much more upvoted) answer based off this one, but this was an excellent solution. Thanks. – Heinrik

Answer 4

If you need first responder just so you can ask it to resign its status, here is an approach to get any to resign. UIView has a method that will iterate through all of UIViews subviews and ask any that are first responder to resign.

[[self view] endEditing:YES];

Here is a link to Apple's UIView Docs "This method looks at the current view and its subview hierarchy for the text field that is currently the first responder. If it finds one, it asks that text field to resign as first responder. If the force parameter is set to YES, the text field is never even asked; it is forced to resign."

Roxannroxanna

I don't think OP wants to force it to resign first responder, just to find the first responder. – Adrastus

Nevertheless, this is a good place for people to discover that snippet. – Micamicaela