Is it safe to set NetworkActivityIndicatorVisible value in secondary thread?

Question

I wonder if AppDelegate is thread safe? I currently have an operation running networking tasks on the secondary thread, when the task begins, I would like to set NetworkActivityIndicatorVisible to YES, and when the task is done, set it to NO. Do I have to always call it in the main thread, or I can do it in the current run loop thread?

Thanks

Answer 1

In general, UIKit is not thread safe. While you may be able to "get away" with some things, you should always do UIKit stuff on the main thread. There are a few, well documented, exceptions.

The pattern for doing this from a background thread is simple.

dispatch_async(dispatch_get_main_queue(), ^{
    // Put any code you want to execute in the main thread here.
});

The code inside the block you pass to dispatch_async will be scheduled to run in the main run loop.