iOS 5的Messages.app鍵盤附件視圖行為

Question

任何人都可以解釋在iOS 5的Messages.app顯示中如何最好地模擬行為“附件視圖”（ 在倒置逗號中，因為我實際上並不認為它是附件視圖 ），因為我想要一個給人印象的視圖它固定在鍵盤的頂部，但是在關閉鍵盤后仍會顯示在屏幕上。

Answer 1

它可能是一個單獨的視圖，該視圖使用與鍵盤動畫具有相同持續時間的動畫進行重新定位。

嘗試觀察UIKeyboardWillShowNotification和UIKeyboardWillHideNotification，並在處理程序中獲取鍵盤的動畫持續時間和幀，並開始自己的動畫以重新放置視圖，以便其隨鍵盤一起移動。 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];
}