Question

Is there a list of which iOS APIs and processes will run when 3rd party apps are in the background? I can’t seem to find anything anywhere so a pointer would be great

Answer 1

Take a look at Apple’s developer document regarding backgrounding.

There’s a finite set of long running tasks that an app can perform in the background, per Apple’s document:

For tasks that require more execution time to implement, you must request specific permissions to run them in the background without their being suspended. In iOS, only specific app types are allowed to run in the background:

• Apps that play audible content to the user while in the background, such as a music player app
• Apps that keep users informed of their location at all times, such as a navigation app
• Apps that support Voice over Internet Protocol (VoIP)
• Newsstand apps that need to download and process new content
• Apps that receive regular updates from external accessories

Apps that implement these services must declare the services they support and use system frameworks to implement the relevant aspects of those services. Declaring the services lets the system know which services you use, but in some cases it is the system frameworks that actually prevent your application from being suspended.