iPad keyboard will not dismiss if modal ViewContro

问题:

Note:

See accepted answer (not top voted one) for solution as of iOS 4.3.

This question is about a behavior discovered in the iPad keyboard, where it refuses to be dismissed if shown in a modal dialog with a navigation controller.

Basically, if I present the navigation controller with the following line as below:

navigationController.modalPresentationStyle = UIModalPresentationFormSheet;

The keyboard refuses to be dismissed. If I comment out this line, the keyboard goes away fine.

...

I\'ve got two textFields, username and password; username has a Next button and password has a Done button. The keyboard won\'t go away if I present this in a modal navigation controller.

WORKS

broken *b = [[broken alloc] initWithNibName:@\"broken\" bundle:nil];
[self.view addSubview:b.view];

DOES NOT WORK

broken *b = [[broken alloc] initWithNibName:@\"broken\" bundle:nil];
UINavigationController *navigationController = 
[[UINavigationController alloc]
 initWithRootViewController:b];
navigationController.modalPresentationStyle = UIModalPresentationFormSheet;
navigationController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:navigationController animated:YES];
[navigationController release];
[b release];

If I remove the navigation controller part and present \'b\' as a modal view controller by itself, it works. Is the navigation controller the problem?

WORKS

broken *b = [[broken alloc] initWithNibName:@\"broken\" bundle:nil];
b.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:b animated:YES];
[b release];

WORKS

broken *b = [[broken alloc] initWithNibName:@\"broken\" bundle:nil];
UINavigationController *navigationController = 
    [[UINavigationController alloc]
         initWithRootViewController:b];
[self presentModalViewController:navigationController animated:YES];
[navigationController release];
[b release];

回答1:

In the viewController that is presented modally just overwrite disablesAutomaticKeyboardDismissal to always return NO

- (BOOL)disablesAutomaticKeyboardDismissal {
    return NO;
}

回答2:

This has been classified as \"works as intended\" by Apple engineers. I filed a bug for this a while back. Their reasoning is that the user is often going to be entering data in a modal form so they are trying to be \"helpful\" and keep the keyboard visible where ordinarily various transitions within the modal view can cause the keyboard to show/hide repeatedly.

edit: here is the response of an Apple engineer on the developer forums:

Was your view by any chance presented with the UIModalPresentationFormSheet style? To avoid frequent in-and-out animations, the keyboard will sometimes remain on-screen even when there is no first responder. This is not a bug.

This is giving a lot of people problems (myself included) but at the moment there doesn\'t seem to be a way to work around it.

UPDATE:

In iOS 4.3 and later, you can now implement `-disablesAutomaticKeyboardDismissal\' on your view controller to return NO:

- (BOOL)disablesAutomaticKeyboardDismissal {
    return NO;
}

This fixes the issue.

回答3:

Be careful if you are displaying the modal with a UINavigationController. You then have to set the disablesAutomaticKeyboardDismissal on the navigation controller and not on the view controller. You can easily do this with categories.

File: UINavigationController+KeyboardDismiss.h

#import <Foundation/Foundation.h>

@interface UINavigationController (KeyboardDismiss)

- (BOOL)disablesAutomaticKeyboardDismissal;

@end

File: UINavigationController+KeyboardDismiss.m

#import \"UINavigationController+KeyboardDismiss.h\"

@implementation UINavigationController(KeyboardDismiss)

- (BOOL)disablesAutomaticKeyboardDismissal
{
    return NO;
}

@end

Do not forget to import the category in the file where you use the UINavigationController.

回答4:

I solved this by using the UIModalPresentationPageSheet presentation style and resizing it immediately after I present it. Like so:

viewController.modalPresentationStyle = UIModalPresentationPageSheet;
viewController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:viewController animated:YES];
viewController.view.superview.autoresizingMask = 
    UIViewAutoresizingFlexibleTopMargin | 
    UIViewAutoresizingFlexibleBottomMargin;    
viewController.view.superview.frame = CGRectMake(
    viewController.view.superview.frame.origin.x,
    viewController.view.superview.frame.origin.y,
    540.0f,
    529.0f
);
viewController.view.superview.center = self.view.center;
[viewController release];

回答5:

If you toggle a different modal display you can get the keyboard to disappear. It\'s not pretty and it doesn\'t animate down, but you can get it to go away.

It\'d be great if there was a fix, but for now this works. You can wedge it in a category on UIViewController and call it when you want the keyboard gone:

@interface _TempUIVC : UIViewController
@end

@implementation _TempUIVC
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return YES;
}
@end

@implementation UIViewController (Helpers)

- (void)_dismissModalViewController {
    [self dismissModalViewControllerAnimated:NO];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidHideNotification object:nil];
    [self release];
}

- (void)forceKeyboardDismissUsingModalToggle:(BOOL)animated {
    [self retain];
    _TempUIVC *tuivc = [[_TempUIVC alloc] init];
    tuivc.modalPresentationStyle = UIModalPresentationCurrentContext;
    [self presentModalViewController:tuivc animated:animated];
    if (animated) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_dismissModalViewController) name:UIKeyboardDidHideNotification object:nil];
    } else
        [self _dismissModalViewController];
    [tuivc release];
}

@end

Be careful with this though as you viewDidAppear / viewDidDisappear and all those methods get called. Like I said, it\'s not pretty, but does work.

-Adam

回答6:

You could also work around this in a universal app by simply checking the idiom and if it\'s an iPad, don\'t pop up the keyboard automatically at all and let the user tap whatever they want to edit.

May not be the nicest solution but it\'s very straightforward and doesn\'t need any fancy hacks that will break with the next major iOS release :)

回答7:

For those having trouble with UINavigationController, see my answer to a similar question here: https://stackoverflow.com/a/10507689/321785

Edit: I consider this an improvement to Miha Hribar\'s solution (since the decision is taking place where it should), and as opposed to Pascal\'s comment regarding a category on UIViewController

回答8:

Put this code in your viewWillDisappear: method of current controller is another way to fix this:

Class UIKeyboardImpl = NSClassFromString(@\"UIKeyboardImpl\");
id activeInstance = [UIKeyboardImpl performSelector:@selector(activeInstance)];
[activeInstance performSelector:@selector(dismissKeyboard)];

回答9:

I\'m sure you have looked at this, but you are sure that your controller class is properly hooked up as the UITextField delegate, right?

回答10:

maybe don\'t return NO, but YES. So it can go away.

And you have a textFieldShouldEndEditing returning YES as well?

And why are you firing [nextResponder becomeFirstResponder]?! sorry i see now

I also have a number of UITextViews which all have their \"editable\" property set to FALSE.

May we assume none of them, by any chance, has a tag value of secondField.tag+1? If so, you\'re telling them to become first responder, instead of resigning the first responder. Maybe put some NSLog() in that if structure.

回答11:

may be not a perfect solution ,but works
[self.view endEditing:YES];
from wherever your button or gesture is implemented to present modal

回答12:

I found that disablesAutomaticKeyboardDismissal and adding a disablesAutomaticKeyboardDismissal function didn\'t work for my UITextField in a modal dialog.

The onscreen keyboard just wouldn\'t go away.

My solution was to disable all text-input controls in my dialog, then re-enable the relevant ones a fraction of a second later.

It seems as though when iOS sees that none of the UITextField controls are enabled, then it does get rid of the keyboard.

回答13:

Swift 4.1:
extension UINavigationController {
   override open var disablesAutomaticKeyboardDismissal: Bool {
      return false
   }
}