core-animation

I'm trying to make a donut shape with CALayers. One CALayer will be a large circle, the other one will be a smaller circle positioned in its center, masking it. The large circle displays fine, but whenever I call circle.mask = circleMask; then the view appears empty. Here's my code: AriDonut.h #import <UIKit/UIKit.h> @interface AriDonut : UIView -(id)initWithRadius:(float)radius; @end AriDonut.m #import "AriDonut.h" #import <QuartzCore/QuartzCore.h> @implementation AriDonut -(id)initWithRadius:(float)radius{ self = [super initWithFrame:CGRectMake(0, 0, radius, radius)]; if(self){ //LARGE

I want to create a CALayer animation that gives sort of a 'flashy' effect. For that I'm trying to animate the 'opacity' property, but my problem is that I have no idea where to start and how to do it. Here is a graphical explanation of the animation: opacity | ___ 1 | | | | | | * repeatCount 0 |___| |_ . . . -------------------------> time |______| duration The opacity starts at 0, then animates to 1, then to 0 again (this 0-to-1-to-0 animation takes a number of seconds equal to duration). Then this process is repeated 'repeatCount' times. Here's some background on the code: float duration = .

To implement a 2D animation I am looking for interpolating values between two key frames with the velocity of change defined by a Bezier curve. The problem is Bezier curve is represented in parametric form whereas requirement is to be able to evaluate the value for a particular time. To elaborate, lets say the value of 10 and 40 is to be interpolated across 4 seconds with the value changing not constantly but as defined by a bezier curve represented as 0,0 0.2,0.3 0.5,0.5 1,1. Now if I am drawing at 24 frames per second, I need to evaluate the value for every frame. How can I do this ? I