UIKeyBoardWIllShowNotification調用一次的原因是什麼？

我正在使用keyboardWasShown和keyboardWillBeHidden通知來滑動視圖以獲取可見的文本視圖。UIKeyBoardWIllShowNotification調用一次的原因是什麼？

我有一個UITabBar應用程序與六個選項卡。

在每個視圖中，我使用UINavigationController。

在每個UITableViewCell的詳細視圖中，我正在使用鍵盤通知。

所以問題是，我第一次使用鍵盤通知。在其他選項卡上它不會工作。

的代碼如下：

[[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; 
}

來源

2009-12-11 harshalb

您也可以從通知的userInfo中獲取animationDuration值。 – Morion 2009-12-11 13:22:59

這些方法和觀察者添加位置在哪裏？ – Morion 2009-12-11 13:24:33

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

你應該eachClass dothis這樣的：

-(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]; 
}

因爲通知是在應用程序級別不在您的課程級別。所以，如果你將它們添加到一個班級而不是所有班級，那麼就去下一堂課。該通知仍然會調用密鑰keyboardWasShown:，另一個來自您添加通知的類，因此您的本地變量如... viewMoved = YES;

keyboardShown = YES;

將拋出壞過剩例外

在你的情況下，還需要在所有6個視圖控制器做

希望這有助於。

來源

2009-12-11 14:00:46

UIKeyBoardWIllShowNotification調用一次的原因是什麼？

回答

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