I had spent weeks looking for ways to make the silent notification more reliable as one of my app's functionality critically depends on it. So far, I couldn't find a satisfactory solution. During the course of it, I find that indeed the notifications are delivered and reach the device, but on the device, a daemon plays a gatekeeper and rejects it unless the device is in a state that meets multiple criteria. To check this in detail, connect your device to the console, and in its search box, add "dads" (it's the name of the daemon) & "your apps name".
Use your app or a 3rd party app such as "Push Hero" (that allows easy generation of app targetted push notifications both alert- and silent-type) and examine what is printed out on the console under the set search criteria. You will find messages like:
com.apple.pushLaunch.<your App ID>:627306:[
{name: DeviceActivityPolicy, policyWeight: 5.000, response: {Decision: Can Proceed, Score: 0.67}}] sumScores:95.343333, denominator:97.010000, FinalDecision: Can Proceed FinalScore: 0.982820}
I found numerous criteria (CPU Usage, Device Polity, Thermal, ThunderingHerdEvents, DataBudgetPolicy, BatteryLevelPolicy...) that will affect "FinalDecision" to become "Should Not Proceed". That is when your silent notification (already on your device) is silently ignored to wake up the App. This is probably to prevent apps from abusing APNs to drain the battery or deteriorate performance, but even for a very small amount of tiny APNs, it gets harder than for a camel to pass through the eye of a needle. Virtual useless as far as my app is concerned. What a shame it is... Please post a reply if you came across a more up-to-date resolution for this issue. I'd appreciate it.
