Silent push notifications only delivered if device is charging and/or app is foreground

Question

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

- (void)application:(         


        

Answer 1

I've been experiencing this problem for some time, and am very grateful for this question and @Kevin D. sharing their understanding. I'm beginning to think that https://stackoverflow.com/a/30834566/1449799 and https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Chapters/CommunicatingWIthAPS.html#//apple_ref/doc/uid/TP40008194-CH101-SW4 (see priority in one of the tables) are describing why my app is having trouble:

It is an error to use this priority for a push that contains only the content-available key.

To send the notifications, I'm using node-apn where the default (which i also need) is to set the priority to max (10 [beware, it looks like only 10 and 5 are correct values at this time]), but since i wanted a silent notification, i don't have alert, badge, or sound set.

Answer 2

I hope you are using APNS delivering priority as "CONSERVE_POWER" (5), try to change it as "IMMEDIATE" (10)

Answer 3

I had experienced the same problem and the reason behind not receiving push notification while the app is not charging is that when the Low Power Mode is enabled from Settings > Battery it disables background-fetch feature for all applications.

Which prevents device from receiving push notification.

This link might be useful. Apple Documentation

Answer 4

It's not working because you have enabled the wrong background mode in the plist. You need to enable the remote-notification tag (App downloads content in response to push notifications), not fetch. Fetch is used for something else. You may also need to use the content available key in your JSON payload, e.g.,

{
   "aps": {
      "content-available": 1
    },
    "yourdatakey":{data}
}

Answer 5

With iOS8 background push delivery to apps has changed. A background push will now only be delivered to the app under certain circumstances. Apple have not stated explicitly what these circumstances exactly are but from my extensive experimentation it basically comes down to if the phone is being charged or not. There are some other variables at play (such as network type, device type, wifi enabled) but the major major major factor is whether the device is being charged or not when the push arrives.

If the phone is being charged via a direct mains power supply or indirectly by being connected by USB to a computer then the background pushes will get delivered to the app the vast majority of the time. But disconnect the phone from the power supply or USB and the background push will almost never get delivered to the app, even if the phone's batter has a 100% charge.

You can very easily test this for yourself just by sending some pushes while the phone is being charged versus while its not. BUT you must take into account that background pushes with a development build and using the sandbox environment DO NOT behave the same as background pushes with a production build and a production environment, the background pushes are actually more likely to be delivered to the app in development then they are in production so it is vital you test using a production build and Apple's production environment to see the actual results.

Note there are two steps the push delivery, the first is it needs to get delivered to the phone itself, the second is once the phone has it, it then needs to get delivered by the OS to the app. In iOS7 things such as turing on Wifi made the chances of the push getting to the phone increase. With iOS8 however even though the push is successfully being delivered to the phone, the OS is not forwarding it on to a background app if the phone isn't being charged. This means the phone gets the notification and holds on to it, sometimes for several hours, before it might forward it to the app if the phone isn't being charged.

Answer 6

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.