我正在尝试Silent Push Notification在我的应用程序中定期实施，即每天一次将数据上传到服务器。
但在iOS 11.2.6上，它始终无法调用委托方法
-(void) application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))
completionHandler无声推送通知。
在设备日志中，我可以看到收到了静默推送通知，但应用程序启动被取消DuetActivitySchedulerDaemon（根据日志）。
你能帮我解决这个问题吗？以下是设备的日志。
Apr 11 21:44:59 iPhone- SpringBoard(UserNotificationsServer)[2696] <Notice>: [com.***.***-myapp] Received remote notification request 91E8-DC24 [ hasAlertContent: 0, hasSound: 0 hasBadge: 0 hasContentAvailable: 1 hasMutableContent: 0 ]
Apr 11 21:44:59 iPhone- SpringBoard(UserNotificationsServer)[2696] <Notice>: [com.***.***-myapp] Deliver push notification request 91E8-DC24.
Apr 11 21:44:59 iPhone- SpringBoard(UserNotificationsServer)[2696] <Notice>: [com.***.***-myapp] Passing content-available push to Duet.
Apr 11 21:44:59 iPhone- SpringBoard(DuetActivityScheduler)[2696] <Notice>: SUBMITTING: <private>.
Apr 11 21:44:59 iPhone- SpringBoard(UserNotificationsServer)[2696] <Error>: Ignoring notification with no alert, sound or badge (com.***.***-myapp): 91E8-DC24
Apr 11 21:44:59 iPhone- SpringBoard(UserNotificationsServer)[2696] <Notice>: [com.***.***-myapp] Not saving push notification 91E8-DC24 to store [ error=Error Domain=UNErrorDomain Code=1401 "Notification has no user-facing content" UserInfo={NSLocalizedDescription=Notification has no user-facing content} ]
Apr 11 21:44:59 iPhone- dasd(DuetActivitySchedulerDaemon)[163] <Notice>: Submitted Activity: com.apple.pushLaunch.com.***.***-myapp:88F855 <private>
Apr 11 21:44:59 iPhone- dasd(DuetActivitySchedulerDaemon)[163] <Notice>: Daemon Canceling Activities: {(
com.apple.pushLaunch.com.***.***-myapp:88F855 )}
Apr 11 21:44:59 iPhone- dasd(DuetActivitySchedulerDaemon)[163] <Notice>: CANCELED: com.apple.pushLaunch.com.***.***-myapp:88F855 <private>!
它确实在其他操作系统中工作了一段时间，并完全停止直到下一次启动。