make animation continues on multi layers by using CAAnimation - ios

Question

I'm creating a tutorial screen to let user understand what to do in the screen.
For example, I have viewPlug and viewBulb. First, viewPlug moves up until it collide viewBulb. After that viewBulb changes color to green to notify. After some seconds, viewPlug moves down and viewBulb changes to red immediately.
So far, I'm digging in UIViewAnimation and UIViewKeyframeAnimation but none of them give me full right to handle complex animation, duration, beginTime... Only CAAnimation can do exactly what I want in scenarios.
But I'm not sure if this is a best way to do in my case, or iOS supports other methods that easier/simpler to handle?
Here is my sample code.
- (void)makeAnimations {
// Group all animation into 1 transaction
[CATransaction begin];
// Create plug animation
CABasicAnimation *animatePlug = [CABasicAnimation animationWithKeyPath:#"position.y"];
animatePlug.beginTime = 0;
animatePlug.byValue = #(-180);
animatePlug.duration = 1.5;
animatePlug.fillMode =kCAFillModeForwards;
animatePlug.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
// Create unplug animation
CABasicAnimation *animateUnplug = [CABasicAnimation animationWithKeyPath:#"position.y"];
animateUnplug.beginTime = 4;
animateUnplug.byValue = #100;
animateUnplug.duration = 0.25;
animateUnplug.fillMode =kCAFillModeForwards;
animateUnplug.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
// Group all animation of view A
CAAnimationGroup *animateGroupPosition = [CAAnimationGroup animation];
animateGroupPosition.duration = 6;
animateGroupPosition.animations = #[animatePlug, animateUnplug];
animateGroupPosition.repeatCount = HUGE_VALF;
[self.viewPlug.layer addAnimation:animateGroupPosition forKey:#"position"];
// Create plug color animation
CABasicAnimation *animateGreen = [CABasicAnimation animationWithKeyPath:#"backgroundColor"];
animateGreen.toValue = (__bridge id)([UIColor greenColor].CGColor);
animateGreen.beginTime = 1.5;
animateGreen.duration = 0.5;
animateGreen.fillMode =kCAFillModeForwards;
// Create unplug color animation
CABasicAnimation *animateRed = [CABasicAnimation animationWithKeyPath:#"backgroundColor"];
animateRed.toValue = (__bridge id)([UIColor redColor].CGColor);
animateRed.beginTime = 4;
animateRed.duration = 0.1;
animateRed.fillMode =kCAFillModeForwards;
// Group all animation of view B
CAAnimationGroup *animateGroupColor = [CAAnimationGroup animation];
animateGroupColor.duration = 6;
animateGroupColor.animations = #[animateGreen, animateRed];
animateGroupColor.repeatCount = HUGE_VALF;
[self.viewBulb.layer addAnimation:animateGroupColor forKey:#"color"];
[CATransaction commit];
}