Detect collisions with UIAnimation

Question

Im using this code to try to detect collisions between two images, one of which is in an animation, but it doesn't work.

[UIView animateWithDuration:5 animations:^{
        bird.center = CGPointMake(bird.center.x, 600);
        fallTimer = [NSTimer scheduledTimerWithTimeInterval:.001 target:self selector:@selector(check) userInfo:nil repeats:YES];
    }];

-(void)check {
    if (CGRectIntersectsRect(bird.frame, cat.frame)) {
        NSLog(@"YES");
    }
}

How can i detect the collision?

Your time interval is ridiculously small (.001 seconds). It looks like bird's position is static in that code. Is the cat moving and could you do your check in the cat animation? — Michael Dautermann, Jul 18 '13 at 22:24

score 0 · Answer 1 · answered Jul 18 '13 at 23:14

0

You can't use the frame of a view while it's being animated, the returned value will not be accurate. Instead, you should be able to get the presentationLayer from the views layer and check its frame.

answered Jul 18 '13 at 23:14

Wain

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Instead of `bird.frame`, try `bird.layer.presentationLayer.frame`. – Wain Jul 19 '13 at 06:50
Tried it, got an error of: Property 'frame' not found on object of type 'id'. Any other ideas? – Sarabyte Studios Jul 19 '13 at 16:23
You'll need to cast the `presentatiomLayer` as a `CALayer` as it's returned as `id`. – Wain Jul 19 '13 at 22:27

Detect collisions with UIAnimation

1 Answers1