Question

I’m noticing in my code that when I try to start an NSTimer from a secondary thread, it doesn’t work. I tried calling +[NSRunLoop currentRunLoop] just in case the problem was that the thread didn’t have a run loop…but no dice. (Note that that was a shot in the dark. The docs said that would create a run loop, but perhaps there’s other configuration that I needed to do, and didn’t.)

I’m aware of calls like -[NSObject performSelectorOnMainThread:] which could solve my problem (in fact, my solution was to simply move this code into the primary thread, which works fine), but I’m still curious about why this problem occurred. Is it in fact impossible to start an NSTimer from a secondary thread? Is there a workaround?

Thanks very much.

Answer 1

Make sure you A) add the timer to the current runloop, and B) run said runloop. When your timer fires, if you’d like to exit the [runloop run] invocation, call [runloop stop].