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?

Answer 1

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]

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Answer 2

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.