Question

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How can I animate the movement of a view or image along a curved path?

I have an iOS application that I want to animate a falling leaf (or several). I have my leaf image in an ImageView and I’ve figured out a simple animation from the documentation:

[UIView animateWithDuration:4.0f
                          delay:0
                          options:UIViewAnimationTransitionFlipFromLeft
                          animations:^(void)
                          {
                              leaf1ImageView.frame = CGRectMake(320, 480, leaf1ImageView.frame.size.width,leaf1ImageView.frame.size.height);
                          }
                          completion:NULL];

This will make the leaf go from its starting position to the bottom right corner in a straight line. How would I animate this to follow a path or curve like a parabola or sinusoid and maybe even rotate the image or view? Would this be done in the animations block? Thanks in advance!

Answer 1

You can do this with a CAKeyframeAnimation and a CGPath. The code looks something like this:

CAKeyframeAnimation *leafAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
leafAnimation.duration = 10.0;
leafAnimation.path = /* your CGPathRef */;
[leaf1ImageView.layer addAnimation:leafAnimation forKey:@"leafAnimation"];