UIKeyBoardWIllShowNotification调用一次的原因是什么？

我正在使用keyboardWasShown和keyboardWillBeHidden通知来滑动视图以获取可见的文本视图。UIKeyBoardWIllShowNotification调用一次的原因是什么？

我有一个UITabBar应用程序与六个选项卡。

在每个视图中，我使用UINavigationController。

在每个UITableViewCell的详细视图中，我正在使用键盘通知。

所以问题是，我第一次使用键盘通知。在其他选项卡上它不会工作。

的代码如下：

[[NSNotificationCenter defaultCenter] addObserver:self 
             selector:@selector(keyboardWasShown:) 
              name:UIKeyboardDidShowNotification 
              object:nil]; 
[[NSNotificationCenter defaultCenter] addObserver:self 
             selector:@selector(keyboardWasHidden:) 
              name:UIKeyboardDidHideNotification 
              object:nil];

和方法

- (void)keyboardWasShown:(NSNotification *)aNotification { 
    if (keyboardShown) 
     return; 


     NSDictionary *info = [aNotification userInfo]; 
     NSValue *aValue = [info objectForKey:UIKeyboardBoundsUserInfoKey]; 
     CGSize keyboardSize = [aValue CGRectValue].size; 

     NSTimeInterval animationDuration = 0.300000011920929; 
     CGRect frame = self.view.frame; 
     frame.origin.y -= keyboardSize.height-100; 
     frame.size.height += keyboardSize.height-100; 
     [UIView beginAnimations:@"ResizeForKeyboard" context:nil]; 
     [UIView setAnimationDuration:animationDuration]; 
     self.view.frame = frame; 
     [UIView commitAnimations]; 

    viewMoved = YES; 

    keyboardShown = YES; 
} 
- (void)keyboardWasHidden:(NSNotification *)aNotification { 
    if (viewMoved && tvAddreview) { 
     NSDictionary *info = [aNotification userInfo]; 
     NSValue *aValue = [info objectForKey:UIKeyboardBoundsUserInfoKey]; 
     CGSize keyboardSize = [aValue CGRectValue].size; 

     NSTimeInterval animationDuration = 0.300000011920929; 
     CGRect frame = self.view.frame; 
     frame.origin.y += keyboardSize.height-100; 
     frame.size.height -= keyboardSize.height-100; 
     [UIView beginAnimations:@"ResizeForKeyboard" context:nil]; 
     [UIView setAnimationDuration:animationDuration]; 
     self.view.frame = frame; 
     [UIView commitAnimations]; 

     viewMoved = NO; 
    } 

    keyboardShown = NO; 
}

来源

2009-12-11 harshalb

您也可以从通知的userInfo中获取animationDuration值。 – Morion 2009-12-11 13:22:59

这些方法和观察者添加位置在哪里？ – Morion 2009-12-11 13:24:33

我在viewDidLoad – harshalb 2009-12-12 06:29:02

你应该eachClass dothis这样的：

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

    NSNotificationCenter *nc = [NSNotificationCenter defaultCenter]; 
    [nc addObserver:self 
      selector:@selector(keyboardWasShown:) 
       name:UIKeyboardWillShowNotification 
      object:nil]; 
    [nc addObserver:self 
      selector:@selector(keyboardWasHidden:) 
       name:UIKeyboardWillHideNotification 
      object:nil]; 

} 

- (void) viewWillDisappear: (BOOL)animated{ 

    [super viewWillDisappear:animated]; 

    NSNotificationCenter *nc = [NSNotificationCenter defaultCenter]; 
    [nc removeObserver:self 
        name:UIKeyboardWillShowNotification 
       object:nil]; 
    [nc removeObserver:self 
        name:UIKeyboardWillHideNotification 
       object:nil]; 
}

因为通知是在应用程序级别不在您的课程级别。所以，如果你将它们添加到一个班级而不是所有班级，那么就去下一堂课。该通知仍然会调用密钥keyboardWasShown:，另一个来自您添加通知的类，因此您的本地变量如... viewMoved = YES;

keyboardShown = YES;

将抛出坏过剩例外

在你的情况下，还需要在所有6个视图控制器做

希望这有助于。

来源

2009-12-11 14:00:46

UIKeyBoardWIllShowNotification调用一次的原因是什么？

回答

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