Earlier this month I mentioned a library for creating a high performance blurring effect which could move while still maintaining a good frame rate called MSLiveBlur.
Here is an open source Swift based library for creating customizable blur animations with good performance called SABlurImageView submitted by Taiki Suzuki.
SABlurIMageView allows you to add a configurable blur effect to any image view, and you can animate with a configurable duration, and also reverse the animation.
Here is an animation from the readme showing SABlurIMageView in action:
You can find SABlurImageView on Github here.
A nice library for creating animated blur effects.