CGRectIntersects子视图的摘要

Question

我使用两个UIImageViews，我已经添加到每个UIImageView的子视图（UIView）。我使用CGRectIntersectsRect来检测碰撞，但不起作用。所以，我有：

这是第一次的UIImageView

hand = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 13.5, 176)]; 
[hand setImage:[UIImage imageNamed:@"hand0.png"]]; 
[hand setContentMode:UIViewContentModeScaleAspectFit]; 

/// Add SUBVIEW which needs to be detected for collision 
hView = [[UIView alloc]initWithFrame:CGRectMake(3, 12, 7, 10)]; 
[hView setBackgroundColor:[UIColor redColor]]; 
[hand addSubview:hView]; 
[hand bringSubviewToFront:hView]; 

hand.center = self.view.center; 
[self.view addSubview:hand]; 

这里是第二的UIImageView

ball = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 33.5, 176)]; 
[ball setImage:[UIImage imageNamed:@"ball0.png"]]; 
[ball setContentMode:UIViewContentModeScaleAspectFit]; 

/// Add SUBVIEW to detect for collision 
bView = [[UIView alloc]initWithFrame:CGRectMake(3, 155, 28, 10)]; 
[bView setBackgroundColor:[UIColor greenColor]]; 
[ball addSubview:bView]; 
[ball bringSubviewToFront:bView]; 

ball.center = self.view.center; 
[self.view addSubview:ball]; 

这里是我的碰撞检测，那里每第二个代码。

- (void)checkCollision 
{ 
    if (CGRectIntersectsRect(bView.frame, hView.frame)) { 
     //do something here 
    } 
} 

任何想法为什么它不检测碰撞？我唯一想到的是因为hView和bView是UIImageView的子视图。

Answer 1

问题是，bView和hView的帧是相对于它们各自的超级浏览。你需要将它们的帧转换为一个共同的祖先，以便它们能够被正确比较。视图控制器的视图将是一个很好的候选人。

- (void)checkCollision { 
    CGRect hFrame = [hView convertRect:hView.bounds toView:self.view]; 
    CGRect bFrame = [bView convertRect:bView.bounds toView:self.view]; 

    if (CGRectIntersectsRect(bFrame, hFrame)) { 
     //do something here 
    } 
}