的iOS 5的Messages.app鍵盤附件查看行爲

Question

誰能解釋如何最好地模仿行爲「附屬視圖」（在倒逗號，因爲我實際上不認爲它是附屬視圖 ）在iOS 5的Messages.app顯示中，我想要一個視圖，它給人的印象是它固定在鍵盤的頂部，但當鍵盤被解散時它仍然保留在屏幕上。

Answer 1

它可能是一個單獨的視圖，它使用與鍵盤動畫具有相同持續時間的動畫重新定位。

嘗試觀察UIKeyboardWillShowNotification和UIKeyboardWillHideNotification，並在您的處理程序中獲取鍵盤的動畫持續時間和框架，並啓動您自己的動畫以重新定位視圖，以使其看起來與鍵盤一起移動。我使用的一些類似代碼如下：

- (void)registerKeyboardNotifications { 
    // Register for keyboard notifications 
    [[NSNotificationCenter defaultCenter] addObserver:self 
              selector:@selector(keyboardWillShow:) 
               name:UIKeyboardWillShowNotification 
               object:nil]; 
    [[NSNotificationCenter defaultCenter] addObserver:self 
              selector:@selector(keyboardWillHide:) 
               name:UIKeyboardWillHideNotification 
               object:nil]; 
} 

- (void)unregisterKeyboardNotifications { 
    [[NSNotificationCenter defaultCenter] removeObserver:self 
                name:UIKeyboardWillShowNotification 
                object:nil];  
    [[NSNotificationCenter defaultCenter] removeObserver:self 
                name:UIKeyboardWillHideNotification 
                object:nil];  
} 

- (void)keyboardWillShow:(NSNotification*)aNotification { 
    NSDictionary* info = [aNotification userInfo]; 
    CGRect kbFrameBeginFrame = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue]; 
    CGRect kbFrameEndFrame = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];  
    NSTimeInterval animDuration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];  
    UIViewAnimationCurve animCurve = [[info objectForKey:UIKeyboardAnimationCurveUserInfoKey] intValue];  

    NSLog(@"\nFrame Begin = %@\nFrame End = %@\nAnimation Duration = %f\nAnimation Curve = %i", 
      NSStringFromCGRect(kbFrameBeginFrame), NSStringFromCGRect(kbFrameEndFrame), animDuration, animCurve); 

    _showKeyboard = YES; 
    [self adjustUIForKeyboard:kbFrameEndFrame.size animDuration:animDuration]; 
} 

- (void)keyboardWillHide:(NSNotification*)aNotification { 
    NSDictionary* info = [aNotification userInfo]; 
    CGRect kbFrameBeginFrame = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue]; 
    CGRect kbFrameEndFrame = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];  
    NSTimeInterval animDuration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];  
    UIViewAnimationCurve animCurve = [[info objectForKey:UIKeyboardAnimationCurveUserInfoKey] intValue]; 

    NSLog(@"\nFrame Begin = %@\nFrame End = %@\nAnimation Duration = %f\nAnimation Curve = %i", 
      NSStringFromCGRect(kbFrameBeginFrame), NSStringFromCGRect(kbFrameEndFrame), animDuration, animCurve); 

    _showKeyboard = NO; 
    [self adjustUIForKeyboard:kbFrameEndFrame.size animDuration:animDuration]; 
} 

/** 
* Adjust the UI elements so that views are visible when keyboard is visible or hidden 
*/ 
- (void)adjustUIForKeyboard:(CGSize)keyboardSize animDuration:(NSTimeInterval)duration {  
    [UIView animateWithDuration:duration 
        animations:^(void) { 
         // When keyboard is showing we adjust up and vice versa for a hidden keyboard 
         if (_showKeyboard) { 
          // Set your view's frame values 
         } else { 
          // Set your view's frame values        
         } 
        } 
        completion:NULL]; 
}