Restoring animation where it left off when app resumes from background

Question

I have an endlessly looping CABasicAnimation of a repeating image tile in my view:

a = [CABasicAnimation animationWithKeyPath:@\"position\"];
a         


        

Answer 1

I was able to restore the animation (but not the animation position) by saving a copy of the current animation and adding it back on resume. I called startAnimation on load and when entering the foreground and pause when entering the background.

- (void) startAnimation {
    // On first call, setup our ivar
    if (!self.myAnimation) {
        self.myAnimation = [CABasicAnimation animationWithKeyPath:@"transform"];
        /*
         Finish setting up myAnimation
         */
    }

    // Add the animation to the layer if it hasn't been or got removed
    if (![self.layer animationForKey:@"myAnimation"]) {
        [self.layer addAnimation:self.spinAnimation forKey:@"myAnimation"];
    }
}

- (void) pauseAnimation {
    // Save the current state of the animation
    // when we call startAnimation again, this saved animation will be added/restored
    self.myAnimation = [[self.layer animationForKey:@"myAnimation"] copy];
}