如何找出两个物体是否相互交叉？

Question

我使用以下代码来创建对象并为其设置动画

//For creating two imageview 
UIImageView *bbl1Obj=[[UIImageView alloc]initWithFrame:CGRectMake(34,77,70, 70)];
bbl1Obj.image=[UIImage imageNamed:@"bubble1.png"];
[self.view addSubview:bbl1Obj];
UIImageView *bbl2Obj=[[UIImageView alloc]initWithFrame:CGRectMake(224,77,70, 70)];
bbl2Obj.image=[UIImage imageNamed:@"bubble2.png"];
[self.view addSubview:bbl2Obj];
// for animating the objects
[UIImageView beginAnimations:nil context:NULL];
[UIImageView setAnimationDuration:3];
[bbl1Obj setFrame:CGRectMake(224,77,70, 70)];
[UIImageView commitAnimations];

[UIImageView beginAnimations:nil context:NULL];
[UIImageView setAnimationDuration:3];
[bbl2Obj setFrame:CGRectMake(34,77,70, 70)];
[UIImageView commitAnimations];

我想在两个图像相互交叉时显示图像.但我不知道如何在动画时找到图像是否相交.任何人都可以告诉我如何在动画时找到两个图像是否相互交叉.

提前致谢

Answer 1

这是我通常用来测试交叉口的东西.但是,我不确定它是否适用于动画中期.

if(CGRectIntersectsRect(bbl1Obj.frame, bbl2Obj.frame)) {

    //They are intersecting
}

它在当前动画时不适用于测试交叉点,尝试使用presentationLayer视图层的属性.以下presentationLayer是来自CALayer类参考的内容:

表示层

返回包含所有属性的图层副本,与当前事务开始时一样,并应用任何活动动画.

考虑到这一点,您现在可以尝试:

CALayer *bbl1ObjPresentationLayer = (CALayer*)[bb1Obj.layer presentationLayer];
CALayer *bbl2ObjPresentationLayer = (CALayer*)[bb2Obj.layer presentationLayer];

if(CGRectIntersectsRect(bbl1ObjPresentationLayer.frame, bbl2ObjPresentationLayer.frame)) {

    //They are intersecting
}

因此,如果第一种方式不起作用,第二种方式肯定会.