应用程序在 iOS 11 中处于后台时未收到推送通知

Question

我正在使用 UNUserNotificationCenter 在 iOS 中发送推送通知。

当应用程序处于前台状态时，我能够收到通知。但是当App处于后台状态时，并没有收到通知。每当应用程序进入前台状态时，才会收到通知。

注册远程通知：

if(SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"10.0")) {
    [UNUserNotificationCenter currentNotificationCenter].delegate = self;
    [[UNUserNotificationCenter currentNotificationCenter] requestAuthorizationWithOptions:(UNAuthorizationOptionSound | UNAuthorizationOptionAlert | UNAuthorizationOptionBadge) completionHandler:^(BOOL granted, NSError * _Nullable error){
        if( !error ){
            dispatch_async(dispatch_get_main_queue(), ^{
                [[UIApplication sharedApplication] registerForRemoteNotifications];
            });
        }
        else{
            NSLog( @"Push registration FAILED" );
            NSLog( @"ERROR: %@ - %@", error.localizedFailureReason, error.localizedDescription );
            NSLog( @"SUGGESTIONS: %@ - %@", error.localizedRecoveryOptions, error.localizedRecoverySuggestion );
        }
    }];
}
else {
    [[UIApplication sharedApplication] registerUserNotificationSettings:[UIUserNotificationSettings settingsForTypes:(UIUserNotificationTypeSound | UIUserNotificationTypeAlert | UIUserNotificationTypeBadge) categories:nil]];
    [[UIApplication sharedApplication] registerForRemoteNotifications];
}

当应用处于前台模式时，调用该方法：

- (void)userNotificationCenter:(UNUserNotificationCenter *)center
   willPresentNotification:(UNNotification *)notification
     withCompletionHandler:(void (^)(UNNotificationPresentationOptions))completionHandler

但此方法在后台模式下不起作用。 我提到了一些 StackOverflow 问题，但无法解决问题。 iOS 11 版有什么要添加的吗？

Answer 1

如果是远程通知，则在应用委托中调用此方法：

    - (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
    fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
//Handle notification here!
    }