在关闭UIAlertView后如何防止UIKeyboard动画回退

Question

I'm wondering if any iOS devs here have ran into this issue and might be able to propose a solution. It involves the behavior of the UIKeyboard as it relates to a UITextView and UIAlertView.

In an app, tapping a UITextView invokes the UIKeyboard. Tapping a button in the UITextView's accessory view invokes a UIAlertView with the UIAlertViewStyleLoginAndPasswordInput style. So far all is good.

Here's the badness: dismissing the UIAlertView causes the UIKeyboard to animate away, and then back as the UITextView becomes the first responder again. The desired behavior is to skip the animation. Calling [textView becomeFirstResponder] in the UIAlertViewDelegate methods doesn't seem to do the trick.

Here is a sample project that illustrates the behavior, and a relevant code snippet and log is posted below.

Thoughts on this?

- (void)viewDidLoad
{
    [super viewDidLoad];

    UIBarButtonItem *alertButton = [[UIBarButtonItem alloc] initWithTitle:@"Alert" style:UIBarButtonItemStyleBordered target:self action:@selector(handleAlertButtonTapped:)];
    UIBarButtonItem *spacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
    UIBarButtonItem *doneButton = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleBordered target:self action:@selector(handleDoneButtonTapped:)];
    UIToolbar *toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0.0, 0.0, self.view.frame.size.width, 44.0)];
    toolbar.barStyle = UIBarStyleBlack;
    toolbar.items = @[alertButton, spacer, doneButton];

    UIView *accessoryView = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, self.view.frame.size.width, 44.0)];
    [accessoryView addSubview:toolbar];
    textView.inputAccessoryView = toolbar;

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardDidHide:) name:UIKeyboardDidHideNotification object:nil];

}


- (void)handleAlertButtonTapped:(id)sender {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Styled AlertView"
                                                        message:nil
                                                       delegate:self
                                              cancelButtonTitle:@"OK"
                                              otherButtonTitles:nil, nil];
    [alertView setAlertViewStyle:UIAlertViewStyleLoginAndPasswordInput];
    [alertView show];
}


- (void)handleDoneButtonTapped:(id)sender {
    [textView resignFirstResponder];
}


#pragma mark -
#pragma mark TextView Delegate Methods

- (BOOL)textViewShouldEndEditing:(UITextView *)textView {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    return YES;
}


- (void)textViewDidEndEditing:(UITextView *)textView {
    NSLog(@"%@", NSStringFromSelector(_cmd));
}


#pragma mark -
#pragma mark AlertView Delegate methods

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    [textView becomeFirstResponder]; // Not a solution.
}

- (void)alertView:(UIAlertView *)alertView willDismissWithButtonIndex:(NSInteger)buttonIndex {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    [textView becomeFirstResponder]; // Not a solution.
}

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    [textView becomeFirstResponder]; // Not a solution.
}


#pragma mark -
#pragma mark Keyboard Notification Methods

- (void)handleKeyboardWillShow:(NSNotification *)notification {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    [textView becomeFirstResponder]; // Not a solution.
}


- (void)handleKeyboardDidShow:(NSNotification *)notification {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    [textView becomeFirstResponder]; // Not a solution.
}


- (void)handleKeyboardWillHide:(NSNotification *)notification {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    [textView becomeFirstResponder]; // Not a solution.
}


- (void)handleKeyboardDidHide:(NSNotification *)notification {
    NSLog(@"%@", NSStringFromSelector(_cmd));
    [textView becomeFirstResponder]; // Not a solution.
}

And the result of the logs is something like this:

ResponderTest[1228:11303] handleKeyboardWillShow:
ResponderTest[1228:11303] handleKeyboardDidShow:
ResponderTest[1228:11303] handleAlertButtonTapped:
ResponderTest[1228:11303] handleKeyboardWillShow:
ResponderTest[1228:11303] handleKeyboardDidShow:
ResponderTest[1228:11303] alertView:clickedButtonAtIndex:
ResponderTest[1228:11303] alertView:willDismissWithButtonIndex:
ResponderTest[1228:11303] handleKeyboardWillHide:
ResponderTest[1228:11303] handleKeyboardDidHide:
ResponderTest[1228:11303] handleKeyboardWillShow:
ResponderTest[1228:11303] handleKeyboardDidShow:
ResponderTest[1228:11303] handleKeyboardWillHide:
ResponderTest[1228:11303] handleKeyboardDidHide:
ResponderTest[1228:11303] handleKeyboardWillShow:
ResponderTest[1228:11303] alertView:didDismissWithButtonIndex:
ResponderTest[1228:11303] handleKeyboardDidShow:

Answer 1

Unless I misunderstood your application structure, it seems like you're over complicating things with all those resignFirstResponder and becomeFirstResponder for UIAlertView dismiss.

Essentially you got a UIAlertView with Username and Password fields yeah?

Add a UIToolBar with a "Done" button that has a callback method like so:

// ------------------------------------------
// Setup keyboard done button as input
// accessory view for your two fields
// ------------------------------------------
UIToolbar *toolBar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
[toolBar setBarStyle:UIBarStyleBlackTranslucent];

UIButton *btnDone = [[UIButton alloc] initWithFrame:CGRectMake(230, 4, 66, 35)];
[btnDone setImage:[UIImage imageNamed:@"btnDoneOff.png"] forState:UIControlStateNormal];
[btnDone setImage:[UIImage imageNamed:@"btnDoneOn.png"] forState:UIControlStateHighlighted];

// ------------------------------------------
// Done button calls hideKeyboard method
// when tapped, this is the only place you
// need to call resign first responder
// ------------------------------------------
[btnDone addTarget:self action:@selector(hideKeyboard) forControlEvents:UIControlEventTouchUpInside];

[toolBar addSubview:btnDone];

[btnDone release];

fldUsername.inputAccessoryView = toolBar;
fldPassword.inputAccessoryView = toolBar;


...

// ------------------------------------------
// Resigns first responder for the two fields
// ------------------------------------------
-(void)hideKeyboard
{
    [fldUsername resignFirstResponder];
    [fldPassword resignFirstResponder];
}

Doing it like this, you can tap either the username field or the password field, the keyboard should not dismiss. When you're done entering username and password, pressing the "Done" button in your keyboard input accessory view will hide the keyboard without causing the keyboard to slide in and out.