Transitions in SwiftUI

Transition.swift

struct ContentView: View {
    @State var flag = false

    var body: some View {
        VStack(spacing: 0) {
            Circle().fill(Color.orange)
            if flag {
                Circle()
                    .fill(Color.red)
                    .transition(.opacity)
                    .animation(.default)
            }
        }
        .background(Color.black.ignoresSafeArea())
        .onTapGesture {
            withAnimation {
                flag.toggle()
            }
        }
    }
}