iOS 使 View 智能地跟随另一个 View

Question

我有以下问题:
我有一个可以通过触摸拖动的 UIImageView 和一个工具栏，我希望它靠近该 ImageView 。这就是我现在正在做的事情:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
  //motion here;self.tool is toolbar View

  CGFloat a=self.tool.frame.size.width;
  CGFloat b=self.tool.frame.size.height;
  self.tool.frame=CGRectMake(self.frame.origin.x+self.frame.size.width/2+50, self.frame.origin.y+self.frame.size.height/2+50, a, b);
}

它工作正常，但有时工具栏会移到屏幕之外。也许有一种简单的方法可以跟踪我是否在外面并将工具栏移动到另一个点？

Answer 1

你可以这样检查:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
  //motion here;self.tool is toolbar View

  CGFloat a = self.tool.frame.size.width;
  CGFloat b = self.tool.frame.size.height;
  CGRect newFrame = CGRectMake(self.frame.origin.x+self.frame.size.width/2+50, 
                               self.frame.origin.y+self.frame.size.height/2+50,
                               a, b);

  // only set frame, if it is still in the bounds of self.superview
  if(CGRectContainsRect(self.superview.frame, newFrame)) {
    self.tool.frame = newFrame;
  }
}