Question

I have a small question, I have a code to generate 200 UIImages in random positions and rotations.

I need to detect the touch event on these images, but I need to check if the touched UIImage is not covered by any other image (even if they intersect in a small area).

Can anybody help me on this?

BTW : I’m trying to do something similar to this game : http://www.dressup247.com/game/1014/Bank-Note-Stack.html

Answer 1

I would suggest to make all images as UIButton‘s with background image and set for all buttons one action. One more advise – set tag order for every button from most low-lying to most high-lying (and store biggest tag in some iVar). You can do it when layout is generated. It allows you to detect how many views lay over tapped view.

Use CGRectIntersectsRect intersecting views.

-(IBAction)banknotTapped:(UIButton*)sender{
    int tag = sender.tag

    NSMutableArray *highestViews = [NSMutableArray array];

    for (int i=sender.tag; i < biggestTag; ++i){
       UIView *v = [self.view viewWithTag:i];
       if (CGRectIntersectsRect(sender.frame, v.frame) ) // it allows to find intersecting views 
           [highestViews addObject:v];
    }
}

Now highestViews will contain all highest views that intersect with sender.

Note: tags allow you to detect views, but if you will delete images from superview then it can lead to problems since tag order will broken. Hide views instead of deleting or follow @Costique method in order to determine views order.