iOS的10及更高版本：
1）userNotificationCenter willPresent通知：一般用來決定何時用戶已經在應用程序中，並通知到達該怎麼辦。您可能會在應用程序內觸發遠程通知。在他點擊遠程通知後，方法2（didReceive響應）被調用。
@available(iOS 10.0, *)
func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (_ options: UNNotificationPresentationOptions) -> Void) {
//Handle push from foreground
//When a notification arrives and your user is using the app, you can maybe notify user by showing a remote notification by doing this
completionHandler([.alert, .badge, .sound])
//To print notification payload:
print(notification.request.content.userInfo)
}
2）userNotificationCenter didReceive響應：一般用於將用戶重定向到用戶敲擊該通知後該應用的特定屏幕。
@available(iOS 10.0, *)
func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping() -> Void) {
//Handle push from background or closed (or even in foreground)
//This method is called when user taps on a notification
//To print notification payload:
print(response.notification.request.content.userInfo)
}
下面的iOS 10：
3）應用didReceiveRemoteNotification：
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any],
fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
//To print notification payload
print(userInfo)
if #available(iOS 10.0, *) {
}
else {
//Handle remote notifications for devices below iOS 10
if application.applicationState == .active {
//app is currently in foreground
}
else if application.applicationState == .background {
//app is in background
}
else if application.applicationState == .inactive {
//app is transitioning from background to foreground (user taps notification)
}
}
}
4）應用didFinishLaunchingWithOptions launchOptions：其被放置裝置之下的iOS 10的唯一情形當應用程序關閉時，用戶點擊啓動應用程序的通知。您必須檢查以下方法。
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
//To print notification payload:
if let notification = launchOptions?[UIApplicationLaunchOptionsKey.remoteNotification] as? [AnyHashable: Any] {
print(notification)
}
}
LaunchOptions是指示該應用是 推出的原因（如果有的話）的字典。在用戶直接啓動應用程序的情況下，此字典的內容可能爲空，如 。
現在回答你的問題，
1）處理遠程通知時應用程序在後臺/無效，你必須添加代碼方法2（userNotificationCenter didReceive響應）與設備iOS 10及以上版本。另外，對於iOS 10以下的設備，您必須使用方法3（應用程序didReceiveRemoteNotification）。
2）要在iOS 10之前的應用程序在前臺運行時處理遠程通知，請使用方法3活動狀態。