Conservation of Mass Jump

Playground.swift

import UIKit
import PlaygroundSupport
import SwiftUI

struct ContentView: View {
    
    var jumpAmount: CGFloat {
        CGFloat(-time * time + time)
    }
    var scaleX: CGFloat { 1/scaleY }
    var scaleY: CGFloat {
        minScale + (jumpAmount * ((1 + maxScale) - minScale))
    }
    var translateY: CGFloat { -translateYAmount * jumpAmount }
    
    @State var time: Double = 0
    
    var minScale: CGFloat = 1
    var maxScale: CGFloat = 0.5
    var translateYAmount: CGFloat = 200
    
    var body: some View {
            Text("😃")
            .font(.largeTitle)
            .scaleEffect(.init(width: scaleX, height: scaleY))
            .offset(x: 0, y: translateY)
            .animation(Animation
                        .linear(duration: 0.3)
                        .repeatForever(autoreverses: true)
            )
            .onAppear {
                self.time = 0.5
            }
    }
}

PlaygroundPage.current.liveView = UIHostingController(rootView: ContentView().frame(width: 320, height: 480))