[rimantas]

  > iOS didn't have multitasking until a lot later, and the
  > concept of background services is more aggressively
  > policed (that is, processes killed often) on iOS, as far
  > as I know?

Ugh, of course iOS had multitasking from the very beginning as you would expect from unix kernel. The access to it from third party apps is entirely different question.

[socrates2014]

iOS had restricted multitasking exposed to apps for awhile (definitely by iOS 5) but it was restricted to certain kinds of apps: VOIP, background audio, newsstand, location awareness, or to a restricted period of time after the app is backgrounded.

They expanded it quite a bit in iOS 7? to all apps with background fetch, background url upload and download tasks, silent push notifications, and background tasks.

All of these approaches do not work if a user forcibly shuts down the app (I am not quite sure of every case). All these mechanisms are controlled by the OS: we'll call you, don't call us sort of thing and if you don't return in a certain period of time or if we need to, we will shut you down.

In iOS 8 you have extension support which launches mini apps. Extensions are somewhat equivalent to services but they are about integration with multitasking an implementation detail for security purposes.

[nailer]

Well yes, without UX it may as well not exist.

[72deluxe]

Yes I meant that it wasn't available to common app developers; of course the system did multitasking and time-sharing!