在不使用私有 API 的情况下获取当前的第一响应者

Question

I submitted my app a little over a week ago and got the dreaded rejection email today. It tells me that my app cannot be accepted because I'm using a non-public API; specifically, it says,

The non-public API that is included in your application is firstResponder.

Now, the offending API call is actually a solution I found here on SO:

UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow];
UIView   *firstResponder = [keyWindow performSelector:@selector(firstResponder)];

How do I get the current first responder on the screen? I'm looking for a way that won't get my app rejected.

Answer 1

如果你的最终目标只是让第一响应者辞职，这应该有效： [self.view endEditing:YES]

Answer 2

In one of my applications I often want the first responder to resign if the user taps on the background. For this purpose I wrote a category on UIView, which I call on the UIWindow.

The following is based on that and should return the first responder.

@implementation UIView (FindFirstResponder)
- (id)findFirstResponder
{
    if (self.isFirstResponder) {
        return self;        
    }
    for (UIView *subView in self.subviews) {
        id responder = [subView findFirstResponder];
        if (responder) return responder;
    }
    return nil;
}
@end

iOS 7+

- (id)findFirstResponder
{
    if (self.isFirstResponder) {
        return self;
    }
    for (UIView *subView in self.view.subviews) {
        if ([subView isFirstResponder]) {
            return subView;
        }
    }
    return nil;
}

Swift:

extension UIView {
    var firstResponder: UIView? {
        guard !isFirstResponder else { return self }

        for subview in subviews {
            if let firstResponder = subview.firstResponder {
                return firstResponder
            }
        }

        return nil
    }
}

Usage example in Swift:

if let firstResponder = view.window?.firstResponder {
    // do something with `firstResponder`
}

Answer 3

A common way of manipulating the first responder is to use nil targeted actions. This is a way of sending an arbitrary message to the responder chain (starting with the first responder), and continuing down the chain until someone responds to the message (has implemented a method matching the selector).

For the case of dismissing the keyboard, this is the most effective way that will work no matter which window or view is first responder:

[[UIApplication sharedApplication] sendAction:@selector(resignFirstResponder) to:nil from:nil forEvent:nil];

This should be more effective than even [self.view.window endEditing:YES] .

(Thanks to BigZaphod for reminding me of the concept)

Answer 4

Here's a category that allows you to quickly find the first responder by calling [UIResponder currentFirstResponder] . Just add the following two files to your project:

UIResponder+FirstResponder.h

#import <Cocoa/Cocoa.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

The trick here is that sending an action to nil sends it to the first responder.

(I originally published this answer here: https://stackoverflow.com/a/14135456/322427 )

Answer 5

Here is a Extension implemented in Swift based on Jakob Egger's most excellent answer:

import UIKit

extension UIResponder {
    // Swift 1.2 finally supports static vars!. If you use 1.1 see: 
    // http://stackoverflow.com/a/24924535/385979
    private weak static var _currentFirstResponder: UIResponder? = nil
    
    public class func currentFirstResponder() -> UIResponder? {
        UIResponder._currentFirstResponder = nil
        UIApplication.sharedApplication().sendAction("findFirstResponder:", to: nil, from: nil, forEvent: nil)
        return UIResponder._currentFirstResponder
    }
    
    internal func findFirstResponder(sender: AnyObject) {
        UIResponder._currentFirstResponder = self
    }
}

---

Swift 4

import UIKit    

extension UIResponder {
    private weak static var _currentFirstResponder: UIResponder? = nil
    
    public static var current: UIResponder? {
        UIResponder._currentFirstResponder = nil
        UIApplication.shared.sendAction(#selector(findFirstResponder(sender:)), to: nil, from: nil, for: nil)
        return UIResponder._currentFirstResponder
    }
    
    @objc internal func findFirstResponder(sender: AnyObject) {
        UIResponder._currentFirstResponder = self
    }
}

Answer 6

It's not pretty, but the way I resign the firstResponder when I don't know what that the responder is:

Create an UITextField, either in IB or programmatically. Make it Hidden. Link it up to your code if you made it in IB.

Then, when you want to dismiss the keyboard, you switch the responder to the invisible text field, and immediately resign it:

    [self.invisibleField becomeFirstResponder];
    [self.invisibleField resignFirstResponder];

Answer 7

对于 Swift 3 & 4 版本的nevyn答案：

UIApplication.shared.sendAction(#selector(UIView.resignFirstResponder), to: nil, from: nil, for: nil)

Answer 8

Here's a solution which reports the correct first responder (many other solutions won't report a UIViewController as the first responder, for example), doesn't require looping over the view hierarchy, and doesn't use private APIs.

It leverages Apple's method sendAction:to:from:forEvent: , which already knows how to access the first responder.

We just need to tweak it in 2 ways:

• Extend UIResponder so it can execute our own code on the first responder.
• Subclass UIEvent in order to return the first responder.

Here is the code:

@interface ABCFirstResponderEvent : UIEvent
@property (nonatomic, strong) UIResponder *firstResponder;
@end

@implementation ABCFirstResponderEvent
@end

@implementation UIResponder (ABCFirstResponder)
- (void)abc_findFirstResponder:(id)sender event:(ABCFirstResponderEvent *)event {
    event.firstResponder = self;
}
@end

@implementation ViewController

+ (UIResponder *)firstResponder {
    ABCFirstResponderEvent *event = [ABCFirstResponderEvent new];
    [[UIApplication sharedApplication] sendAction:@selector(abc_findFirstResponder:event:) to:nil from:nil forEvent:event];
    return event.firstResponder;
}

@end

Answer 9

The first responder can be any instance of the class UIResponder, so there are other classes that might be the first responder despite the UIViews. For example UIViewController might also be the first responder.

In this gist you will find a recursive way to get the first responder by looping through the hierarchy of controllers starting from the rootViewController of the application's windows.

You can retrieve then the first responder by doing

- (void)foo
{
    // Get the first responder
    id firstResponder = [UIResponder firstResponder];

    // Do whatever you want
    [firstResponder resignFirstResponder];      
}

However, if the first responder is not a subclass of UIView or UIViewController, this approach will fail.

To fix this problem we can do a different approach by creating a category on UIResponder and perform some magic swizzeling to be able to build an array of all living instances of this class. Then, to get the first responder we can simple iterate and ask each object if -isFirstResponder .

This approach can be found implemented in this other gist .

Hope it helps.

Answer 10

Using Swift and with a specific UIView object this might help:

func findFirstResponder(inView view: UIView) -> UIView? {
    for subView in view.subviews as! [UIView] {
        if subView.isFirstResponder() {
            return subView
        }
        
        if let recursiveSubView = self.findFirstResponder(inView: subView) {
            return recursiveSubView
        }
    }
    
    return nil
}

Just place it in your UIViewController and use it like this:

let firstResponder = self.findFirstResponder(inView: self.view)

Take note that the result is an Optional value so it will be nil in case no firstResponder was found in the given views subview hierarchy.

Answer 11

迭代可能是第一响应者的视图并使用- (BOOL)isFirstResponder来确定它们当前是否是。

Answer 12

Peter Steinberger 刚刚发布了关于私有通知UIWindowFirstResponderDidChangeNotification推文，如果你想观看 firstResponder 的变化，你可以观察它。

Answer 13

If you just need to kill the keyboard when the user taps on a background area why not add a gesture recognizer and use it to send the [[self view] endEditing:YES] message?

you can add the Tap gesture recogniser in the xib or storyboard file and connect it to an action,

looks something like this then finished

- (IBAction)displayGestureForTapRecognizer:(UITapGestureRecognizer *)recognizer{
     [[self view] endEditing:YES];
}

Answer 14

Just it case here is Swift version of awesome Jakob Egger's approach:

import UIKit

private weak var currentFirstResponder: UIResponder?

extension UIResponder {

    static func firstResponder() -> UIResponder? {
        currentFirstResponder = nil
        UIApplication.sharedApplication().sendAction(#selector(self.findFirstResponder(_:)), to: nil, from: nil, forEvent: nil)
        return currentFirstResponder
    }

    func findFirstResponder(sender: AnyObject) {
        currentFirstResponder = self
    }

}

Answer 15

This is what I did to find what UITextField is the firstResponder when the user clicks Save/Cancel in a ModalViewController:

    NSArray *subviews = [self.tableView subviews];

for (id cell in subviews ) 
{
    if ([cell isKindOfClass:[UITableViewCell class]]) 
    {
        UITableViewCell *aCell = cell;
        NSArray *cellContentViews = [[aCell contentView] subviews];
        for (id textField in cellContentViews) 
        {
            if ([textField isKindOfClass:[UITextField class]]) 
            {
                UITextField *theTextField = textField;
                if ([theTextField isFirstResponder]) {
                    [theTextField resignFirstResponder];
                }

            }
        }

    }

}

Answer 16

I have a slightly different approach than most. Rather than iterate through the collection of views looking for the one that has isFirstResponder set, I too send a message to nil , but I store the receiver of the message so I can return it and do whatever I wish with it.

import UIKit

private var _foundFirstResponder: UIResponder? = nil

extension UIResponder {

    static var first:UIResponder? {

        // Sending an action to 'nil' implicitly sends it to the first responder
        // where we simply capture it and place it in the _foundFirstResponder variable.
        // As such, the variable will contain the current first responder (if any) immediately after this line executes
        UIApplication.shared.sendAction(#selector(UIResponder.storeFirstResponder(_:)), to: nil, from: nil, for: nil)

        // The following 'defer' statement runs *after* this getter returns,
        // thus releasing any strong reference held by the variable immediately thereafter
        defer {
            _foundFirstResponder = nil
        }

        // Return the found first-responder (if any) back to the caller
        return _foundFirstResponder
    }

    @objc func storeFirstResponder(_ sender: AnyObject) {

        // Capture the recipient of this message (self), which is the first responder
        _foundFirstResponder = self
    }
}

With the above, I can resign the first responder by simply doing this...

UIResponder.first?.resignFirstResponder()

But since my API actually hands back whatever the first responder is, I can do whatever I want with it.

Here's an example that checks if the current first responder is a UITextField with a helpMessage property set, and if so, shows it in a help bubble right next to the control. We call this from a 'Quick Help' button on our screen.

func showQuickHelp(){

    if let textField   = UIResponder?.first as? UITextField,
       let helpMessage = textField.helpMessage {
    
        textField.showHelpBubble(with:helpMessage)
    }
}

The support for the above is defined in an extension on UITextField like so...

extension UITextField {
    var helpMessage:String? { ... }
    func showHelpBubble(with message:String) { ... }
}

Now to support this feature, all we have to do is decide which text fields have help messages and the UI takes care of the rest for us.

Answer 17

With a category on UIResponder , it is possible to legally ask the UIApplication object to tell you who the first responder is.

See this:

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

Answer 18

You can choose the following UIView extension to get it (credit by Daniel) :

extension UIView {
    var firstResponder: UIView? {
        guard !isFirstResponder else { return self }
        return subviews.first(where: {$0.firstResponder != nil })
    }
}

Answer 19

This is what I have in my UIViewController Category. Useful for many things, including getting first responder. Blocks are great!

- (UIView*) enumerateAllSubviewsOf: (UIView*) aView UsingBlock: (BOOL (^)( UIView* aView )) aBlock {

 for ( UIView* aSubView in aView.subviews ) {
  if( aBlock( aSubView )) {
   return aSubView;
  } else if( ! [ aSubView isKindOfClass: [ UIControl class ]] ){
   UIView* result = [ self enumerateAllSubviewsOf: aSubView UsingBlock: aBlock ];

   if( result != nil ) {
    return result;
   }
  }
 }    

 return nil;
}

- (UIView*) enumerateAllSubviewsUsingBlock: (BOOL (^)( UIView* aView )) aBlock {
 return [ self enumerateAllSubviewsOf: self.view UsingBlock: aBlock ];
}

- (UIView*) findFirstResponder {
 return [ self enumerateAllSubviewsUsingBlock:^BOOL(UIView *aView) {
  if( [ aView isFirstResponder ] ) {
   return YES;
  }

  return NO;
 }];
}

Answer 20

This is good candidate for recursion! No need to add a category to UIView.

Usage (from your view controller):

UIView *firstResponder = [self findFirstResponder:[self view]];

Code:

// This is a recursive function
- (UIView *)findFirstResponder:(UIView *)view {

    if ([view isFirstResponder]) return view; // Base case

    for (UIView *subView in [view subviews]) {
        if ([self findFirstResponder:subView]) return subView; // Recursion
    }
    return nil;
}

Answer 21

you can call privite api like this ,apple ignore:

 UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow]; SEL sel = NSSelectorFromString(@"firstResponder"); UIView *firstResponder = [keyWindow performSelector:sel];

Answer 22

I would like to shared with you my implementation for find first responder in anywhere of UIView. I hope it helps and sorry for my english. Thanks

+ (UIView *) findFirstResponder:(UIView *) _view {

    UIView *retorno;

    for (id subView in _view.subviews) {

        if ([subView isFirstResponder])
        return subView;

        if ([subView isKindOfClass:[UIView class]]) {
            UIView *v = subView;

            if ([v.subviews count] > 0) {
                retorno = [self findFirstResponder:v];
                if ([retorno isFirstResponder]) {
                    return retorno;
                }
            }
        }
    }

    return retorno;
}

Answer 23

Swift version of @thomas-müller 's response

extension UIView {

    func firstResponder() -> UIView? {
        if self.isFirstResponder() {
            return self
        }

        for subview in self.subviews {
            if let firstResponder = subview.firstResponder() {
                return firstResponder
            }
        }

        return nil
    }

}

Answer 24

You can try also like this:

- (void) touchesBegan: (NSSet *) touches withEvent: (UIEvent *) event { 

    for (id textField in self.view.subviews) {

        if ([textField isKindOfClass:[UITextField class]] && [textField isFirstResponder]) {
            [textField resignFirstResponder];
        }
    }
} 

I didn't try it but it seems a good solution

Answer 25

The solution from romeo https://stackoverflow.com/a/2799675/661022 is cool, but I noticed that the code needs one more loop. I was working with tableViewController. I edited the script and then I checked. Everything worked perfect.

I recommed to try this:

- (void)findFirstResponder
{
    NSArray *subviews = [self.tableView subviews];
    for (id subv in subviews )
    {
        for (id cell in [subv subviews] ) {
            if ([cell isKindOfClass:[UITableViewCell class]])
            {
                UITableViewCell *aCell = cell;
                NSArray *cellContentViews = [[aCell contentView] subviews];
                for (id textField in cellContentViews)
                {
                    if ([textField isKindOfClass:[UITextField class]])
                    {
                        UITextField *theTextField = textField;
                        if ([theTextField isFirstResponder]) {
                            NSLog(@"current textField: %@", theTextField);
                            NSLog(@"current textFields's superview: %@", [theTextField superview]);
                        }
                    }
                }
            }
        }
    }
}

Answer 26

Code below work.

- (id)ht_findFirstResponder
{
    //ignore hit test fail view
    if (self.userInteractionEnabled == NO || self.alpha <= 0.01 || self.hidden == YES) {
        return nil;
    }
    if ([self isKindOfClass:[UIControl class]] && [(UIControl *)self isEnabled] == NO) {
        return nil;
    }

    //ignore bound out screen
    if (CGRectIntersectsRect(self.frame, [UIApplication sharedApplication].keyWindow.bounds) == NO) {
        return nil;
    }

    if ([self isFirstResponder]) {
        return self;
    }

    for (UIView *subView in self.subviews) {
        id result = [subView ht_findFirstResponder];
        if (result) {
            return result;
        }
    }
    return nil;
}   

Answer 27

Update: I was wrong. You can indeed use UIApplication.shared.sendAction(_:to:from:for:) to call the first responder demonstrated in this link: http://stackoverflow.com/a/14135456/746890 .

---

Most of the answers here can't really find the current first responder if it is not in the view hierarchy. For example, AppDelegate or UIViewController subclasses.

There is a way to guarantee you to find it even if the first responder object is not a UIView .

First lets implement a reversed version of it, using the next property of UIResponder :

extension UIResponder {
    var nextFirstResponder: UIResponder? {
        return isFirstResponder ? self : next?.nextFirstResponder
    }
}

With this computed property, we can find the current first responder from bottom to top even if it's not UIView . For example, from a view to the UIViewController who's managing it, if the view controller is the first responder.

However, we still need a top-down resolution, a single var to get the current first responder.

First with the view hierarchy:

extension UIView {
    var previousFirstResponder: UIResponder? {
        return nextFirstResponder ?? subviews.compactMap { $0.previousFirstResponder }.first
    }
}

This will search for the first responder backwards, and if it couldn't find it, it would tell its subviews to do the same thing (because its subview's next is not necessarily itself). With this we can find it from any view, including UIWindow .

And finally, we can build this:

extension UIResponder {
    static var first: UIResponder? {
        return UIApplication.shared.windows.compactMap({ $0.previousFirstResponder }).first
    }
}

So when you want to retrieve the first responder, you can call:

let firstResponder = UIResponder.first

Answer 28

Simplest way to find first responder:

func sendAction(_ action: Selector, to target: Any?, from sender: Any?, for event: UIEvent?) -> Bool

The default implementation dispatches the action method to the given target object or, if no target is specified, to the first responder.

Next step:

extension UIResponder
{
    private weak static var first: UIResponder? = nil

    @objc
    private func firstResponderWhereYouAre(sender: AnyObject)
    {
        UIResponder.first = self
    }

    static var actualFirst: UIResponder?
    {
        UIApplication.shared.sendAction(#selector(findFirstResponder(sender:)), to: nil, from: nil, for: nil)
        return UIResponder.first
    }
}

Usage: Just get UIResponder.actualFirst for your own purposes.