Responds to selector when services has Implement delegate method

[kagenZhao]

Fix UserNotifications delegate methods implementation. Override "responds(to:)". resolve some warning, such as: "You've implemented -[<UIApplicationDelegate> application:performFetchWithCompletionHandler:], but you still need to add "fetch" to the list of your supported UIBackgroundModes in your Info.plist. You've implemented -[<UIApplicationDelegate> application:didReceiveRemoteNotification:fetchCompletionHandler:], but you still need to add "remote-notification" to the list of your supported UIBackgroundModes in your Info.plist.