how to prevent main thread ios from killing background thread

Question

I have a method in my AppDelegate that saves a NSManagedObjectContext passed as a parameter. This method may be called on either the main thread or a background thread, and I want to ensure that when this method is called the main thread doesn't kill it halfway through when the user terminates the program or what have you. How do I prevent the main thread from killing this thread when this method is being executed?

I also want to do this for writing data to a plist file -- this also may happen outside of the main thread.

I am doing all my background work by way of GCD and dispatch_async

Answer 1

Brad Larson had some suggestions on this post that should help you.

In your appDelegate, when your app is getting pushed to the background, it calls applicationDidEnterBackground . From this routine, you can see if your method is currently in progress, and can behave accordingly.

Depending on how long your task takes to run there are two options:

1. If it will take significantly less than 5 seconds, you can just have your applicationDidEnterBackground wait until your task is completed before releasing. If you take longer than 5 seconds, your app will just get force-killed.

2. If it could be a while, you can try beginBackgroundTaskWithExpirationHandler : to start a background task that finishes off your task.