Don't try to create a whole bunch of separate animations. CAShapeLayer has a strokeStart and strokeEnd property. Animate that.
The trick is to install an arc of the whole circle in the shape layer, then create a CABasicAnimation that animates the shapeEnd from 0 to 1 (to animate the fill from 0% to 100%) or whatever values you need.
You can apply whatever timing you want on that animation.
I have a project (In Objective-C, I'm afraid) on Github that includes a "clock wipe" animation using this technique. Here's how it looks:
(That's a gif, which looks a little rough. The actual iOS animation is quite smooth.)
The link is below. Look for the "clock wipe" animation in the readme.
iOS-CAAnimation-group-demo
The clock wipe animation installs the shape layer as a mask on an image view's layer. You can instead draw your shape layer directly if that's what you want to do.
