iOS：在父視圖上移動子視圖

Question

我是IOS的新手。 在我的應用中，每次用戶繪制一個圓時，我都會創建一個新的圓子視圖。 創建圓后，我希望用戶能夠在父視圖上拖動圓。 如果用戶創建了一個以上的圓圈，我如何知道觸摸了哪個圓圈並將其拖動到屏幕上。

Answer 1

我已經成功實現了自己想要的目標。 我在circle subview覆蓋了touchmoved方法，並在其中輸入以下行：

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *mytouch=[[touches allObjects] objectAtIndex:0];

    self.center = [mytouch locationInView:self.superview];

}

現在，每個創建的circle都可以與屏幕一起拖動。

Answer 2

您可以將平移手勢添加到要移動的位置：

// Add UIPanGestureRecognizer to each circle view u add and set a tag for each circle
UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc]  initWithTarget: self   action: @selector(handlePan:)];
[view addGestureRecognizer:   panRecognizer];


-(void) handlePan: (UIGestureRecognizer *)sender
{
  UIPanGestureRecognizer *panRecognizer = (UIPanGestureRecognizer *)sender;
  UIView *view = sender.view;
// You can get to know which circle was moved by getting tag of this view
  if (panRecognizer.state == UIGestureRecognizerStateBegan ||
      panRecognizer.state ==  UIGestureRecognizerStateChanged)
  {
    CGPoint currentPoint = self.center;
    CGPoint translation =    [panRecognizer translationInView:     self.superView];
    view.center = CGPointMake(currentPoint.x + translation.x,  currentPoint.y + translation.y);
    [panRecognizer setTranslation: CGPointZero inView: self.view];
  }
}