Apple music animated bars - SwiftUI - Swift Playground

Playground.swift

import SwiftUI
import PlaygroundSupport

struct ContentView: View {
    var body: some View {
        Bars()
    }
}

struct Bars:View {
    var body: some View {
            HStack(alignment: .bottom) {
                ForEach((1...10), id: \.self) { value in
                    Bar().foregroundColor(.blue)
                }
            }
        
    }
}

struct Bar:View {
    @State var size: CGFloat = CGFloat(Float.random(in: 0..<1))
    
    @State var nexSize:CGFloat = CGFloat(Float.random(in: 0..<1))
    
    //animation duration in second
    let animationDuration:Double = 1
    
    var animation:Animation {
        Animation.linear(duration: self.animationDuration)
    }
    
    //update size and update nextsize, which will trigger next animation
    func updateSizeAndTriggerNextAnimation(newSize:CGFloat){
        self.size = newSize
        //as there's no completion handler on animation, update nextsize just before current animation end
        DispatchQueue.main.asyncAfter(deadline: .now() + self.animationDuration * 0.8) {
            self.nexSize = CGFloat(Float.random(in: 0..<1)) 
        }
    }
    
    var body: some View {
        HStack(alignment: .bottom){
            RoundedRectangle(cornerRadius: 25)
                .scaleEffect(y:size,anchor: .bottomLeading)
                //On appear trigger animation
                .onAppear() {
                    withAnimation(self.animation) {
                        self.updateSizeAndTriggerNextAnimation(newSize: self.nexSize)
                    }
                }
                //when nextSize change launch new animation
                .onChange(of: nexSize) { [size] newState in
                    withAnimation(self.animation) {
                        self.updateSizeAndTriggerNextAnimation(newSize: self.nexSize)
                    }
                }
        }
        
    }
}

PlaygroundPage.current.needsIndefiniteExecution = true
PlaygroundPage.current.setLiveView(ContentView())