OnAppearVsTask

ContentView.swift

import SwiftUI

struct ContentView: View {
    @State private var color0 = Color.red
    @State private var color1 = Color.red
    var body: some View {
        VStack {
            color0
            color1
        }
        .onAppear { color0 = .green }
        .task { color1 = .green }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}