ios - 当 UIAlertView 在屏幕上时，无法在 UIViewController 堆栈中隐藏键盘

Question

我花了一天的大部分时间来追踪一个非常奇怪的案例，即在事件的 UITextField 上调用 resignFirstResponder 并没有隐藏键盘，即使文本字段是第一响应者。当我将一个 View Controller 推到另一个具有事件文本字段的 View Controller 之上时，就会发生这种情况。键盘消失了(如预期的那样)。但是，如果我通过触摸第二个 View Controller 中的文本字段来恢复键盘，则对 resignFirstResponder 的后续调用无效。

下面是重现问题的简单代码。此代码是一个带有导航栏按钮的 View Controller ，用于隐藏键盘，另一个用于推送自身的另一个副本(带有确认 UIAlertView)。第一份副本没有问题。但是，如果您按下第二个副本(当第一个副本具有可见键盘时)，则无法关闭键盘。只有在推送第二个副本时屏幕上出现 UIAlertView(确认)时才会发生这种情况。如果删除 #define ALERT 行，一切正常。

有人知道这里发生了什么吗？看起来 UIALertView 窗口以某种方式干扰了键盘并阻止它的窗口消失，这会混淆下一个 View 。除了在 UIALertView 消失后将第二个 View Controller 推到计时器上之外，这里还有其他解决方案吗？

对于复杂的描述，我们深表歉意。这是可运行的代码。我希望代码清晰。

@implementation DemoViewController

- (id) init {
    if (!(self = [super init])) 
        return nil;

    return self; 
}

- (void) dealloc {
    [_inputTextfield release];
    [super dealloc];
}

- (void) loadView {
    UIView *view = [[UIView alloc] initWithFrame:[UIScreen mainScreen].bounds];

    _inputTextfield = [[UITextField alloc] initWithFrame:CGRectMake(0., 0., 320., 44.)];
    _inputTextfield.borderStyle = UITextBorderStyleRoundedRect;
    _inputTextfield.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
    _inputTextfield.keyboardAppearance = UIKeyboardAppearanceAlert;
    _inputTextfield.autocapitalizationType = UITextAutocapitalizationTypeNone;
    _inputTextfield.autocorrectionType = UITextAutocorrectionTypeNo;
    _inputTextfield.keyboardType = UIKeyboardTypeDefault;
    [view addSubview:_inputTextfield];

    self.view = view;
    [view release];
}

- (void) viewWillAppear:(BOOL) animated {
    [super viewWillAppear:animated];

    UIButton *downButton = [UIButton buttonWithType:UIButtonTypeCustom];
    [downButton setTitle: @"keyboard down" forState:UIControlStateNormal];
    [downButton addTarget:self action:@selector(downButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
    [downButton sizeToFit];    
    self.navigationItem.leftBarButtonItem = [[[UIBarButtonItem alloc] initWithCustomView:downButton] autorelease];

    UIButton *nextButton = [UIButton buttonWithType:UIButtonTypeCustom];
    [nextButton setTitle: @"next" forState:UIControlStateNormal];
    [nextButton addTarget:self action:@selector(nextButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
    [nextButton sizeToFit];
    self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] initWithCustomView:nextButton] autorelease];;

}

- (void) viewWillDisappear:(BOOL) animated {
[super viewWillDisappear:animated];
    [_inputTextfield resignFirstResponder];
}

- (void) downButtonPressed:(id)sender {
    [_inputTextfield resignFirstResponder];
}

#define ALERT

- (void) alertView:(UIAlertView *) alertView didDismissWithButtonIndex:(NSInteger) buttonIndex {
    if (alertView.cancelButtonIndex == buttonIndex) {
        return; 
    }
    [self _nextButtonPressed];
}

- (void) _nextButtonPressed {
    DemoViewController *nextViewController = [[DemoViewController alloc] init];    
    [self.navigationController pushViewController:nextViewController];
    [nextViewController release];
}

- (void) nextButtonPressed:(id)sender {
#ifdef ALERT   
    UIAlertView *alert = [[UIAlertView alloc] init];
    alert.message = @"Next view?";  
    alert.cancelButtonIndex = [alert addButtonWithTitle:@"No"];
    [alert addButtonWithTitle:@"Yes"];
    alert.delegate = self;
    [alert show];
    [alert release];
#else   
    [self _nextButtonPressed];    
#endif
}

Answer 1

如果您不幸辞去了急救人员的职务，这里有一些可能会有所帮助的解决方案:

1. 确定在您最后一次要求辞去第一响应者之后谁仍然是第一响应者。

2. 尝试通过一次调用 self.view(容器 View )让所有第一响应者辞职

   [self.view endEditing:YES];
   

3. 只有如果您尝试了上述所有方法但均无效，请考虑使用此解决方法。

   -(BOOL)textViewShouldEndEditing:(UITextView *)textView {
     NSArray *wins = [[UIApplication sharedApplication] windows];
     if ([wins count] > 1) {
       UIWindow *keyboardWindow = [wins objectAtIndex:1];
       keyboardWindow.hidden = YES;
     }
     return YES;
   }