CALayer subclass not animating to property changes

Question

I have a CALayer subclass with float animAngle as property marked as @dynamic. I have implemented methods actionForKey, initWithLayer, needsDisplayForKey and drawInContext for subclass. The definition for actionForKey is as follows

- (id<CAAction>)actionForKey:(NString *)event {
    if([event isEqualToString:@"animAngle"]) {
        return [self animationForKey:event];
    }
    return [super actionForKey:event];
}

And

- (CABasicAnimation *)animationForKey:(NSString *)key
{
    NSString *animValue = [[self presentationLayer] valueForKey:key];// Logs as 0
    CABasicAnimation *anim;

    if([key isEqualToString:@"animAngle"]) {
        anim = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
        anim.repeatCount = HUGE_VAL;
        anim.autoreverses = YES;
        //anim.fromValue = [[self presentationLayer] valueForKey:key]; // setting animation value from layer property as in here does not work.
        anim.fromValue = [NSNumber numberWithFloat:0.5f];            // This works
    }
    anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    anim.duration = 0.11;
    return anim;
}

In Someother class:

myCASublayer.animAngle = 0.5f;

Somehow the CABasicAnimation being returned is not able to properly use the layer "animAngle" property. What would i be possibly doing wrong here?

Answer 1

CocoaHeads Session: Rob Napier on Animating Custom Layer Properties is a good presentation about custom animations.

CALayers hate do draw ;)

Answer 2

If animAngle is a @property - you must specify accessors for this property.
When you mark property as @dynamic this means, that you will provide an implementation of those methods dynamically at runtime. So, if you do not provide accessors for property, you can't access it.