Commit A Different Animation(s) While Another Animation is ending - ios

Question

I'm trying to create a 'wave' effect of UIView animations.
I have numerous layers to animate. I'm currently animating them with animateWithDuration:delay:options:animations:completion:
I have the views displayed in a stack so for example:
-------------------------------
| VIEW 1 |
-------------------------------
| VIEW 2 |
-------------------------------
| VIEW 3 |
-------------------------------
| VIEW 4 |
-------------------------------
| VIEW 5 |
-------------------------------
| VIEW 6 |
-------------------------------
This is important to know because UIView transitions are not what I'm going after.
I can easily animate them and concurrently activate the next view animation in the completion block of the previous view. So this is how it's currently set up:
[UIView animateWithDuration:0.4f animations:^{
self.view1.alpha = 1.0;
} completion:^(BOOL finished) {
[UIView animateWithDuration:0.4f animations:^{
self.view2.alpha = 1.0;
} completion:^(BOOL finished) {
etc...
}];
}];
What i would like to do, instead of concurrently activating the next view animation I would like it to activate while the previous views animation is ending. So say, the last half of time in the animation process, start the next views animation to get a wave effect. None of the UIViewAnimationOptions match my criteria, and I've also researched the developer forums for a similar goal, with no results.
What I have tried:
The workaround that I've tried is adding a delay to the next UIView animations inside the animations block as opposed to the completion block, but I feel this isn't a healthy take on the matter. Ex:
[UIView animateWithDuration:0.4f animations:^{
//Other animations...
self.view1.alpha = 1.0f
[UIView animateWithDuration:0.4f delay:0.2f options:UIViewAnimationOptionAllowUserInteraction animations:^{
self.view2.alpha = 1.0f;
} completion:^(BOOL finished) {
//repeat..
}];
}];
As you can see my work around, well, works. But as I stated above, it doesn't feel an iota of healthy. What am I missing?
EDIT
I inevitably went the route of using UIViewAnimationOptions by delaying and autoreversing the durations:
NSTimeInterval duration = 3.0;
NSTimeInterval delay = 0.5f;
[UIView animateWithDuration:duration delay:0.0f options:(UIViewAnimationOptionRepeat | UIViewAnimationOptionAutoreverse | UIViewAnimationOptionAllowUserInteraction) animations:^{
self.view1.alpha = 1.0f;
} completion:^(BOOL finished) {
}];
[UIView animateWithDuration:duration delay:delay options:(UIViewAnimationOptionRepeat | UIViewAnimationOptionAutoreverse | UIViewAnimationOptionAllowUserInteraction) animations:^{
self.view2.alpha = 1.0f;
} completion:^(BOOL finished) {
}];
[UIView animateWithDuration:duration delay:delay*2 options:(UIViewAnimationOptionRepeat | UIViewAnimationOptionAutoreverse | UIViewAnimationOptionAllowUserInteraction) animations:^{
self.view3.alpha = 1.0f;
} completion:^(BOOL finished) {
}];
etc...

Answer 1

You can use CALayer animation instead of UIView animation to achieve this. Just configure the begin time, duration and the animation on each view's layer. Here is a quick Swift example:
for (var i, v) in enumerate(views) {
let animation = CABasicAnimation(keyPath:"opacity")
animation.toValue = 0.0
animation.duration = 0.4
animation.beginTime = CACurrentMediaTime() + 0.2 * i
v.layer.addAnimation(animation, forKey: "wave")
}