Refactoring Massive App Delegate using Composite pattern. See blog post for more details: https://www.vadimbulavin.com/refactoring-massive-app-delegate

RefactoringAppDelegate-Composite.swift

class PushNotificationsAppDelegate: AppDelegateType {
    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        // Registered successfully
    }
}

class StartupConfiguratorAppDelegate: AppDelegateType {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Perform startup configurations, e.g. build UI stack, setup UIApperance
        return true
    }
}

class ThirdPartiesConfiguratorAppDelegate: AppDelegateType {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Setup third parties
        return true
    }
}