The iOS Home Screen wiggle animation, in SwiftUI

Wiggle.swift

import SwiftUI

extension View {
    func wiggling() -> some View {
        modifier(WiggleModifier())
    }
}

struct WiggleModifier: ViewModifier {
    @State private var isWiggling = false
    
    private static func randomize(interval: TimeInterval, withVariance variance: Double) -> TimeInterval {
        let random = (Double(arc4random_uniform(1000)) - 500.0) / 500.0
        return interval + variance * random
    }
    
    private let rotateAnimation = Animation
        .easeInOut(
            duration: WiggleModifier.randomize(
                interval: 0.14,
                withVariance: 0.025
            )
        )
        .repeatForever(autoreverses: true)
    
    private let bounceAnimation = Animation
        .easeInOut(
            duration: WiggleModifier.randomize(
                interval: 0.18,
                withVariance: 0.025
            )
        )
        .repeatForever(autoreverses: true)
    
    func body(content: Content) -> some View {
        content
            .rotationEffect(.degrees(isWiggling ? 2.0 : 0))
            .animation(rotateAnimation)
            .offset(x: 0, y: isWiggling ? 2.0 : 0)
            .animation(bounceAnimation)
            .onAppear() { isWiggling.toggle() }
    }
}

WiggleApp.swift

// An example app to demonstrate the wiggle effect

import SwiftUI

@main
struct WiggleApp: App {
    var body: some Scene {
        WindowGroup {
            ZStack {
                Color.white.ignoresSafeArea()
                HStack(spacing: 30) {
                    CalendarView()
                    WeatherView()
                }
            }
        }
    }
}

struct CalendarView: View {
    var body: some View {
        Widget(color: .black) {
            Text("Wednesday")
            Text("5").font(.system(size: 33))
            
            Spacer()
            
            Text("No more events today")
                .frame(width: 150, height: 45, alignment: .leading)
                .multilineTextAlignment(.leading)
        }
    }
}

struct WeatherView: View {
    let weatherBg = LinearGradient(
        gradient: Gradient(colors: [Color.blue, Color.white]),
        startPoint: .topLeading,
        endPoint: .bottomTrailing
    )
    
    var body: some View {
        Widget(background: weatherBg) {
            Text("Wednesday")
            
            Text("18°")
                .font(.system(size: 44))
                .fontWeight(.thin)
            
            Spacer()
            
            Image(systemName: "cloud.sun.fill")
            
            Text("Partly Cloudy")
                .frame(width: 150, height: 20, alignment: .leading)
            
            Text("H:21° L:12°")
        }
    }
}

struct Widget<Content: View, Background: View>: View {
    let content: Content
    let background: Background
    
    init(background: Background, @ViewBuilder content: () -> Content) {
        self.background = background
        self.content = content()
    }
    
    var body: some View {
        ZStack {
            VStack(alignment: .leading) { content }
                .padding()
                .background(background)
                .cornerRadius(22)
                .foregroundColor(.white)
        }
        .frame(width: 170, height: 170, alignment: .leading)
        .overlay(
            Image(systemName: "minus.circle.fill")
                .font(.title)
                .foregroundColor(Color(.systemGray))
                .background(
                    Color.black
                        .clipShape(Circle())
                        .frame(width: 20, height: 20)
                )
                .offset(x: -80, y: -80)
        )
        .wiggling()
    }
}

extension Widget where Background == Color {
    init(color: Color, @ViewBuilder content: () -> Content) {
        self.init(background: color, content: content)
    }
}

struct WiggleApp_Previews: PreviewProvider {
    static var previews: some View {
        HStack(spacing: 30) {
            CalendarView()
            WeatherView()
        }
        .background(Color.white)
    }
}

Thank you @markmals for sharing! This is very useful 💯

thanks, this was very helpful @markmals

Note that 'animation' was depricated in iOS 15.0: Use withAnimation or animation(_:value:) instead.

But how to switch start or stop animation?