Timeline.playground.swift

import UIKit
import PlaygroundSupport


var str = "Hello, playground"
let view = UIView(frame: CGRect(x: 0, y: 0, width: 600, height: 600))
view.backgroundColor = .red
let bottomLabel = UILabel()
bottomLabel.text = "Hello world!"
bottomLabel.sizeToFit()
bottomLabel.alpha = 0

view.addSubview(bottomLabel)

//animations 
let fadeOutBottomLabel = {
    bottomLabel.alpha = 0
}
let fadeInBottomLabel = {
    bottomLabel.alpha = 1
}
let moveBottomLabelRight = {
    bottomLabel.transform = CGAffineTransform(translationX: 30, y: 0)
}


struct Timeline {

    var keyframes: [(wait: TimeInterval, thenRun: () -> Void, lasting: TimeInterval, curve: UIViewAnimationOptions, Timeline?)]

    public init(_ keyframes: (wait: TimeInterval, thenRun: () -> Void, lasting: TimeInterval, curve: UIViewAnimationOptions, Timeline?)...) {
        self.init(keyframes)
    }

    private init(_ keyframes: [(wait: TimeInterval, thenRun: () -> Void, lasting: TimeInterval, curve: UIViewAnimationOptions, Timeline?)]) {
        print("another way")
        self.keyframes = keyframes

    }

    func run() {
        for frame in keyframes {
            print("frame running")
            UIView.animate(withDuration: frame.lasting, delay: frame.wait, options: frame.curve, animations: {
                frame.thenRun()
            }) { _ in
                frame.4?.run()
            }
        }
    }
  
    static func then(_ keyframes: (wait: TimeInterval, thenRun: () -> Void, lasting: TimeInterval, curve: UIViewAnimationOptions, Timeline?)...) -> Timeline {
        return Timeline(keyframes)
    }
}


PlaygroundPage.current.liveView = view

let timeline = Timeline (
    (wait: 1.0, thenRun: fadeInBottomLabel,    lasting: 5.0, curve: .curveLinear, nil),
    (wait: 1.5, thenRun: moveBottomLabelRight, lasting: 5.0, curve: .curveEaseInOut, .then(
            (wait: 5.0, thenRun: fadeOutBottomLabel, lasting: 5.0, curve: .curveLinear, nil) )))

timeline.run()