UIView Animation, Transforming layer.shadowPath

Question

I created a UIImageView that has a custom shadowPath. This view will be moved left and right across the screen, but I need the shadowPath to have a different transformation than the image layer itself. Is this possible? Moving the image itself works, and the shadow moves as well when I do the following:

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.3];
[UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
im.center = location;
[UIView commitAnimations];

But if I try to add a layer transformation before "commitAnimations", the shadow will simply take on that property right away, for example:

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:5];
[UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
im.center = location;
im.layer.shadowPath = [self createPerspectiveShadow:im]; //this will not animate
[UIView commitAnimations];

So, my question is, is there a way to recalculate a shadow during the animation?

Thanks

score 2 · Accepted Answer · answered Mar 04 '11 at 00:51

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The UIView animations don’t always allow you to animate CALayer attributes; try using a CABasicAnimation instead.

answered Mar 04 '11 at 00:51

Jeff Kelley

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Unfortunately, a CABasicAnimation probably won't cut it because I have to recalculate the entire shadow path. CABasicAnimation.fromValue and .toValue require NSNumbers, and I can't pass a CGPathRef to them instead. Is there something I'm missing? – Mirkules Mar 04 '11 at 01:02
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Hmm, that’s a tough one. You may be better off setting up an `NSTimer` to fire once every 1/60th of a second, then updating the position of the shadow programmatically. Sucks, but it’ll work… – Jeff Kelley Mar 04 '11 at 01:30
I was afraid this was going to come up :) Oh well, I was hoping for a quicker, easier solution. Anyway, thanks for your input Jeff (I'll mark your answer in a day or two...) – Mirkules Mar 04 '11 at 04:55
A bit late but you can definitely animate paths with CABasicAnimation. `fromValue` and `toValue` are `id`, so just do a `(__bridge id)` on the `CGPathRef`. – fumoboy007 Dec 30 '13 at 07:11

score 1 · Answer 2 · edited May 23 '17 at 12:12

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You can pass a CGPathREf to the toValue

theAnimation.toValue = (id)[UIBezierPath bezierPathWithRect:newRect].CGPath;

see this post

edited May 23 '17 at 12:12

Community

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answered Sep 27 '11 at 16:22

Gering

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UIView Animation, Transforming layer.shadowPath

2 Answers2