Implement Robust Mobile Deeplink Handling

As a mobile developer, I need to implement robust deeplink handling across iOS and Android so that users can navigate directly to specific content within my application from external sources. This includes setting up Universal Links for iOS and App Links for Android, and handling deferred deeplinking.

For iOS Universal Links, the setup involves configuring the AppDelegate.swift or SceneDelegate.swift to handle incoming user activities:

// AppDelegate.swift
func application(_ application: UIApplication, 
                continue userActivity: NSUserActivity, 
                restorationHandler: @escaping ([UIUserActivityRestoring]?) -> Void) -> Bool {
    guard userActivity.activityType == NSUserActivityTypeBrowsingWeb, 
          let url = userActivity.webpageURL else { return false } 
    
    return handleDeeplink(url: url)
}

// iOS 13+ SceneDelegate
func scene(_ scene: UIScene, continue userActivity: NSUserActivity) {
    guard let url = userActivity.webpageURL else { return }
    handleDeeplink(url: url)
}

private func handleDeeplink(url: URL) -> Bool {
    let components = URLComponents(url: url, resolvingAgainstBaseURL: true)
    let path = components?.path ?? ""
    
    switch path {
    case let path where path.hasPrefix("/product/"):
        let productId = String(path.dropFirst("/product/".count))
        navigateToProduct(id: productId)
        return true
    case "/profile":
        navigateToProfile()
        return true
    default:
        return false
    }
}