Demo SplaschScreen

DemoSplashScreen.swift

import SwiftUI

struct SplashScreen: View {

    var body: some View {
        ZStack {
            Rectangle().fill(Color.blue.gradient)

            Image(systemName: "apple.logo")
                .resizable()
                .aspectRatio(contentMode: .fit)
                .frame(width: 72)
        }
        .ignoresSafeArea()
    }

}

struct RootView: View {

    var body: some View {
        ZStack {
            Text("Root view")
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(.yellow)
    }
}

struct CustomSplashTransition2: Transition {
    var isRoot: Bool

    func body(content: Content, phase: TransitionPhase) -> some View {
        content.rotation3DEffect(
                .degrees(phase.isIdentity ? 0 : isRoot ? 70 : -70),
                axis: (x: 0, y: 1, z: 0),
                anchor: isRoot ? .leading : .trailing
            )
            .offset(x: phase.isIdentity ? 0 : isRoot ? screenSize.width : -screenSize.width)
    }

    /// Current Screen Size (Without the usage of GeometryReader)
    var screenSize: CGSize {
        if let screenSize = (UIApplication.shared.connectedScenes.first as? UIWindowScene)? .screen.bounds.size {
            return screenSize
        }
        return .zero
    }
}

struct ContentMain: View {
    @State var showsSplashScreen: Bool = true

    var body: some View {
        ZStack {
            if showsSplashScreen {
                SplashScreen()
                    .transition(CustomSplashTransition2(isRoot: false))
            } else {
                RootView()
                    .transition(CustomSplashTransition2(isRoot: true))
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(.black)
        .ignoresSafeArea()
        .task {
            guard showsSplashScreen else { return }
            try? await Task.sleep(for: .seconds(2.5))
            DispatchQueue.main.async {
                withAnimation(.smooth(duration: 0.55)) {
                    showsSplashScreen = false
                }
            }
        }

    }

    var safeArea: UIEdgeInsets {
        if let safeArea = (UIApplication.shared.connectedScenes.first as? UIWindowScene)? .keyWindow?.safeAreaInsets {
            return safeArea
        }
        return .zero
    }

}

#Preview {
    ContentMain()
}