UIPanGestureRecognizer和BringSubviewToFront

Question

我有一個應用程序，用戶點擊一個按鈕，應用程序將實例化一個圖像層（UIImageView）。我想要讓用戶可以移動選定的圖像層，無論他們點擊哪一個。在閱讀了一些主題後，我瞭解到我可以使用UIPanGestureRecognizer來移動選定的圖像層。

- (IBAction)buttonClicked:(id)sender { 
    imageview = [[UIImageView alloc] initWithFrame:CGRectMake(100, 0, 300, 22)]; 
    UIPanGestureRecognizer *imageviewGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(recognizePan:)]; 
    [imageviewGesture setMinimumNumberOfTouches:1]; 
    [imageviewGesture setMaximumNumberOfTouches:1]; 
    imageview.image = [UIImage imageNamed:@"pinimage.png"]; 
    [imageview addGestureRecognizer:imageviewGesture]; 
    [imageview setUserInteractionEnabled:YES]; 
    [self.view addSubview:imageview]; 
    NSUInteger currentag = [self UniqueTag]; // Assigning a unique integer 
    imageview.tag = currentag; 
} 

- (void)recognizePan:(UIPanGestureRecognizer *)sender { 
    [[[(UITapGestureRecognizer *)sender view] layer] removeAllAnimations]; 
    [self.view bringSubviewToFront:[(UIPanGestureRecognizer *)sender view]]; 
    CGPoint translatedPoint = [(UIPanGestureRecognizer *)sender translationInView:self.view]; 

    if([(UIPanGestureRecognizer *)sender state] == UIGestureRecognizerStateBegan) {  
     firstX = [[sender view] center].x; 
     firstY = [[sender view] center].y; 
    } 

    translatedPoint = CGPointMake(firstX + translatedPoint.x,firstY + translatedPoint.y); 
    [[sender view] setCenter:translatedPoint]; 
} 

現在，我無法弄清楚如何在有多個圖像層時將挖掘圖層放在前面。它似乎沒有[self.view bringSubviewToFront：[（UIPanGestureRecognizer *）發送者視圖]]有效。那麼，我該如何修改我的代碼，以便應用程序將觸發層添加到其他層？

謝謝你的幫助。

Answer 1

一個很好的方法是製作一個UIImageView的CustomImageView子類。您將UIPanGestureRecognizer附加到CustomImageView的每個實例，並將該實例設置爲目標。然後，通過手勢觸發的動作方法的觀點本身實現的，所以，你可以參考的觀點與self：

在buttonClicked

MyImageView* imageview = [[MyImageView alloc] initWithFrame:CGRectMake(100, 0, 300, 22)]; 
    UIPanGestureRecognizer *imageviewGesture = 
    [[UIPanGestureRecognizer alloc] initWithTarget:imageview 
              action:@selector(recognizePan:)]; 

在CustomImageView.m

- (void)recognizePan:(UIPanGestureRecognizer *)sender { 
     [self.layer removeAllAnimations]; 
     [self.superview bringSubviewToFront:self]; 
     CGPoint translatedPoint = [sender translationInView:self]; 
     if([sender state] == UIGestureRecognizerStateBegan) { 
      self.firstX = [self center].x; 
      self.firstY = [self center].y; 
     } 
     translatedPoint = CGPointMake(self.firstX + translatedPoint.x, 
             self.firstY + translatedPoint.y); 
     [self setCenter:translatedPoint]; 
    } 

更新

不思考直 - 你當然可以做t他通過訪問gestureRecongnizer的view屬性從viewController中訪問您的操作。你的錯誤是相當這裏：

- (void)recognizePan:(UIPanGestureRecognizer *)sender { 
    [[[(UITapGestureRecognizer *)sender view] layer] removeAllAnimations]; 

您更改發件人類型從UIPanGestureRecognizer到UITapGestureRecognizer。實際上，您不需要在該方法的主體中執行任何sender類型轉換。