gistfile1.m

- (CAAnimation *)rotationAnimation {
    CABasicAnimation *rotation = [CABasicAnimation animationWithKeyPath:@"transform"];

    rotation.valueFunction = [CAValueFunction functionWithName:kCAValueFunctionRotateZ];
    rotation.fromValue = [NSNumber numberWithFloat:0.0];
    rotation.toValue = [NSNumber numberWithFloat:M_PI * 2];
    rotation.duration = 2.0f;
    rotation.repeatCount = INFINITY;
    rotation.removedOnCompletion = NO;

    return rotation;
}

...

[layer addAnimation:[self rotationAnimation] forKey:@"animation"];