Detect end of performSelectorInBackground:withObject:

Question

I have an asynchronous server request in my iOS app:

[self performSelectorInBackground:@selector(doSomething) withObject:nil];

How can I detect the end of this operation?

Answer 1

Put a call at the end of the doSomething method?!

- (void)doSomething {
    // Thread starts here

    // Do something

    // Thread ends here
    [self performSelectorOnMainThread:@selector(doSomethingDone) withObject:nil waitUntilDone:NO];
}

Answer 2

If you just want to know when it's finished (and don't want to pass much data back - at which point I would recommend a delegate) you could simply post a notification to the notification center.

[[NSNotificationCenter defaultCenter] postNotificationName:kYourFinishedNotificationName object:nil];

within your view controllers viewDidLoad method add:

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(yourNotificationListenerMethod:)
                                                 name:kYourFinishedNotificationName
                                               object:nil];

and within dealloc, add:

[[NSNotificationCenter defaultCenter] removeObserver:self];