iOS：在父视图上移动子视图

Question

我是IOS的新手。 在我的应用中，每次用户绘制一个圆时，我都会创建一个新的圆子视图。 创建圆后，我希望用户能够在父视图上拖动圆。 如果用户创建了一个以上的圆圈，我如何知道触摸了哪个圆圈并将其拖动到屏幕上。

Answer 1

我已经成功实现了自己想要的目标。 我在circle subview覆盖了touchmoved方法，并在其中输入以下行：

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

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

}

现在，每个创建的circle都可以与屏幕一起拖动。

Answer 2

您可以将平移手势添加到要移动的位置：

// 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];
  }
}