如何防止 UIKeyboard 在关闭 UIAlertView 后以动画形式离开和返回

Question

我想知道这里是否有任何iOS开发人员遇到过这个问题，也许能够提出解决方案。它涉及UIKeyboard的行为，因为它与UITextView和UIAlertView有关。

在应用中，点击 UITextView 将调用 UIKeyboard。点击 UITextView 附件视图中的按钮将调用具有 UIAlertViewStyleLoginAndPasswordInput 样式的 UIAlertView。到目前为止，一切都很好。

这是不好的：关闭UIAlertView会导致UIKeyboard动画消失，然后在UITextView再次成为第一个响应者时返回。 所需的行为是跳过动画。 在UIAlertViewDelegate方法中调用[textView be成为FirstResponder]似乎并不能解决问题。

下面是一个演示行为的示例项目，下面发布了相关的代码片段和日志。

对此有何看法？

- (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.
}

日志的结果是这样的：

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

除非我误解了您的应用程序结构，否则您似乎将所有这些辞职第一响应者的事情复杂化，并成为UIAlertView解雇的第一响应者。

从本质上讲，您有一个带有用户名和密码字段的UIAlertView是吗？

添加一个带有"完成"按钮的 UIToolBar，该按钮具有如下回调方法：

// ------------------------------------------
// 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];
}

这样做，您可以点击用户名字段或密码字段，键盘不应关闭。输入完用户名和密码后，按键盘输入附件视图中的"完成"按钮将隐藏键盘，而不会导致键盘滑入和滑出。