iOS应用launch screen仅首次显示的实现方案咨询

Hey there! Let's clear up one thing first: Apple's default Launch Screen (configured in LaunchScreen.storyboard/xib) is designed to display briefly every time your app launches, to give users immediate feedback that the app is loading. You can't disable this entirely, but if you want a custom intro/onboarding screen that only shows up the first time someone opens your app, here's exactly how to pull it off:

Core Idea #

We'll use UserDefaults to store a simple flag tracking whether the app has been launched before. When the app starts, we check this flag:

• If it's not set (first launch), show your custom intro screen, then mark the flag as "launched".
• If it is set, skip the intro and go straight to your main app content.

Step-by-Step Implementation #

1. Set Up the Flag Check #

Let's cover both UIKit and SwiftUI since they're the two main frameworks used today.

For UIKit (iOS 13+)

If you're using SceneDelegate, add this logic in the scene(_:willConnectTo:options:) method:

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    guard let windowScene = (scene as? UIWindowScene) else { return }
    
    let window = UIWindow(windowScene: windowScene)
    self.window = window
    
    // Check if app has been launched before
    let hasLaunchedBefore = UserDefaults.standard.bool(forKey: "hasLaunchedBefore")
    
    if hasLaunchedBefore {
        // Navigate to main screen
        let mainVC = MainViewController() // Replace with your main view controller
        window.rootViewController = UINavigationController(rootViewController: mainVC)
    } else {
        // Show custom launch/onboarding screen
        let launchVC = CustomLaunchViewController() // Replace with your custom launch screen VC
        window.rootViewController = UINavigationController(rootViewController: launchVC)
        
        // Mark app as launched
        UserDefaults.standard.set(true, forKey: "hasLaunchedBefore")
        UserDefaults.standard.synchronize() // Optional, ensures immediate save
    }
    
    window.makeKeyAndVisible()
}

For SwiftUI

Use @AppStorage (a handy wrapper around UserDefaults) to simplify the check in your app's entry point:

@main
struct YourApp: App {
    @AppStorage("hasLaunchedBefore") private var hasLaunchedBefore = false
    
    var body: some Scene {
        WindowGroup {
            if hasLaunchedBefore {
                MainContentView() // Your main app content
            } else {
                CustomLaunchView() // Your custom launch/onboarding view
                    .onAppear {
                        // Mark as launched after the view loads
                        hasLaunchedBefore = true
                    }
            }
        }
    }
}

2. Handle Navigation from Custom Launch Screen #

Add a way to navigate to the main app once the user is done with the intro (like a "Get Started" button). For example, in UIKit:

// Inside CustomLaunchViewController
@IBAction func getStartedTapped(_ sender: UIButton) {
    let mainVC = MainViewController()
    // Push to main screen (or replace root to remove back navigation)
    navigationController?.pushViewController(mainVC, animated: true)
}

3. Edge Cases to Consider #

• Uninstall/Reinstall: If the user uninstalls and reinstalls the app, UserDefaults will be cleared, so the custom launch screen will show again (this is usually desired behavior).
• Testing the First Launch Flow: To retest the intro, either uninstall the app, or add a debug-only button to reset the flag:

  // Debug use only!
  UserDefaults.standard.set(false, forKey: "hasLaunchedBefore")
  

内容的提问来源于stack exchange，提问作者prem cool