Question

I am having some problems getting this animation to execute. I have a feeling there are probably a few problems with it, but am having trouble finding the right direction.
I would like to pulse (scale up and down) a CATextLayer while the user is dragging a UISlider control.

Inside the IBAction method I have the following code. I have checked to make sure that the method is actually being called.

CABasicAnimation *pulse = [CABasicAnimation animationWithKeyPath:@"scale"];
pulse.fromValue = [NSNumber numberWithFloat:1.0];
pulse.toValue = [NSNumber numberWithFloat:1.2];
pulse.duration = 1;
pulse.repeatCount = HUGE_VALF;
pulse.autoreverses = YES;
pulse.timingFunction =[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
[self.symbolLayer addAnimation:pulse forKey:nil]; 

I have noticed that the method is called repeatedly very fast, Im not sure if this preventing the animation from going, or there is a problem with the animation block itself.

Answer 1

You want to animate the contentScale property. There is no scale property in CATextLayer.

Alternatively, I’ve found that animating fontSize seems to give me more of the effect I was looking for. It animates the text from the center, whereas animating contentScale seems to animate from one of the corners.