willowtreeapps/spruce-ios — reverse-engineered prompt

Build me a lightweight iOS animation library in Swift that makes it easy to choreograph a whole screen of views instead of animating everything by hand. I want a simple, friendly API on UIView where I can first prepare views for animation, like fading out or shrinking them, and then run the animation later with one call. It should support common effects like fade in, expand, and springy movement, and it should be able to animate subviews in different orders, like top to bottom, radial, or random, with delays between items so the screen feels staged and polished.

Please also make it possible to plug in custom animations with a prepare step and an animate step, so designers and developers can experiment without rewriting the library. Include an example app that shows off the built in animation styles and sort orders, plus enough documentation so someone can quickly copy the basic usage into their own app. Make it feel lightweight and easy to drop into existing iOS projects. If you need details, check current iOS animation docs online.