Silent push notifications only delivered if device

Question

I have implemented silent push notifications but I have noticed some strange behaviour. The silent push notifications are handled via:

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler

The silent push messages only seem to be received if the device is charging (ie cable connected) and/or if my app is foreground.

If I disconnect the device from the charger (or Mac) then the silent push notifications are no longer received unless the app is foreground.

I get non-silent push notifications normally in both cases.

If I plug in the USB cable again, then I get the expected behaviour and silent push notifications are received irrespective of whether the app is foreground or background.

I am using UILocalNotification so I know what is being received.

The fact that it all works fine with the device connected suggests that my silent pushes notifications are configured correctly and that the app has the correct background modes set in the plist etc.

This behaviour is repeatable on iPhone 5s, 6 and iPad 2 all running either IOS 8 or 8.1.

Has anyone else experienced this? It should be easy to reproduce. Why should the simple act of plugging a device into a charger change the ability to receive silent push notifications?

Answer 1

I also noticed the same and wasted some time figuring out. See https://stackoverflow.com/a/31237889/1724763

If you turned off Bg App Refresh, silent remote push will be dropped silently (the irony).

However, my observation is that if you connect to Xcode via cable, somehow the Bg App Refresh setting is ignored and all silent push for your app works.

I highly suspect this is an undocumented feature: charging causes the Bg App Refresh setting to be ignored.

Answer 2

I found another solution that is worked for me using PushKit Framework

VoIP pushes provide additional functionality on top of the standard push that is needed to VoIP apps to perform on-demand processing of the push before displaying a notification to the user

When I send VOIP Push the App wakes up whatever the state of the Application and can perform any operations

Register for VOIP PushNotification in didFinishLaunchingWithOptions

 PKPushRegistry *pushRegistry = [[PKPushRegistry alloc] initWithQueue:dispatch_get_main_queue()];
pushRegistry.delegate = self;
pushRegistry.desiredPushTypes = [NSSet setWithObject:PKPushTypeVoIP];


- (void)pushRegistry:(PKPushRegistry *)registry didUpdatePushCredentials:(PKPushCredentials *)credentials forType:(NSString *)type{
if([credentials.token length] == 0) {
    NSLog(@"voip token NULL");
    return;
}

NSString *originalToken=[NSString stringWithFormat:@"%@",credentials.token];
NSString *token = [originalToken stringByTrimmingCharactersInSet: [NSCharacterSet characterSetWithCharactersInString:@"<>"]];
token = [token stringByReplacingOccurrencesOfString:@" " withString:@""];
NSLog(@"PushCredentials: %@",token);}

then you can handle any background fetch in this function once you receive VOIP PushNotification

-(void)pushRegistry:(PKPushRegistry *)registry didReceiveIncomingPushWithPayload:(PKPushPayload *)payload forType:(NSString *)type

NOTE: you must use certificate that enable VoIP Services Certificate