Rotate a UIView that's already animating w/ rotation

Question

I've been searching around, but couldn't find an answer that seems to address my specific issue. In my app, I have a custom UIView that animates indefinitely. It's a piece of seaweed, and the animation is very subtle, to make it look like it's swaying in water. I do this with CAKeyframeAnimation objects on the transform.rotation.z and position keys. These are added to a CAAnimationGroup, which is added as a layer to my UIView, like so:

animGroup = [CAAnimationGroup animation];
animGroup.fillMode = kCAFillModeForwards;
[animGroup setAnimations:[NSArray arrayWithObjects:posAnim, rotateAnim, nil]];
animGroup.duration = prpAnim.duration;
animGroup.repeatCount = prpAnim.repeat;
animGroup.delegate = self;
[animGroup setValue:self forKey:[NSString stringWithFormat:@"paper.rot.pos.%d",objID]];
[self.layer addAnimation:animGroup forKey:[NSString stringWithFormat:@"rot.pos.%d",objID]];

I want to further rotate that UIView image (piece of seaweed) when tilting the iPad without disturbing the core animation. I can do this when it's not animated by keyframe, but when I try to combine the two, it doesn't work and I can't figure it out.

I've tried animating the layer using something like this:

CATransform3D rotatePiece3D = CATransform3DMakeRotation(-(tiltRadians), 0.0, 0.0, 1.0);
seaweedPiece.layer.transform = rotatePiece3D;

But that doesn't work either - only when the animation group is turned off. It's a 2D app, so I just want it rotate around the z-axis when tilting left or right. Any ideas how to do this?

Answer 1

You apparently can't alter the rotation separately while it's being animated, so what I was trying to do won't work. I ended up changing the animation key to path , which allowed me to rotate the view separately using the accelerometer.