IOS audio procces in swift

General information for the app: music app Kind of development: Customization of existing app Description of requirements/features: I need to make a custom effect for music, my app in Swift language and I want the only class (not app) for my order to make this custom effect, you can use any library like audiokit. the effect makes the music is speeding and smaller this is the example of my effect example 1 original https://www.youtube.com/watch?v=8_e1ZJQez5s after effect https://www.youtube.com/watch?v=NSTOYSsFo0U example 2 original https://www.youtube.com/watch?v=jYjc0EfOu1E after effect https://www.youtube.com/watch?v=Q4fwDoqpyEM Extra notes: