You can create local notifications any time your app is active, which includes the background. AFAIK signal does empty APNS push to wake and then pulls data wi

You can create local notifications any time your app is active, which includes the background. AFAIK signal does empty APNS push to wake and then pulls data with it's own connection and then displays text content with a local notification. The main reason for the restriction to apple-only for notification services is battery life, and they've been proven right by bad behavior demonstrated on android. Interestingly, if your a VOIP app you can actually circumvent a lot of the background networking restrictions, but it's still hard to do when you don't have an active call in place. You also have to be an actual VOIP app to get approved with that entitlement. Which wouldn't be hard to get approval for if you made a fork of signal for example, since it does have real VOIP capabilities inside. Either way the battery life of your device would be worse with your custom VOIP app always keeping a connection open vs. apple's native OS notification system.