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I have a serious problem with NSTimer. I noticed when I have NSTimer running, and it’s cranking through the selector method, if I click on a menu or some other similar object in the UI, the NSTimer won’t do anything - loop, increment, whatever…. it just stops. Of course, once the menu is no longer active (if I click off or something), then the NSTimer continues on its merry way. I want that NSTimer to keep looping and everything as it is told, whether it’s key, or a menu is clicked or whatever. Barring some act of God or computer death of some sort, I want that NSTimer instance to keep going. How do I do that? I’m surprised I didn’t notice this before, and it’s not the desired behavior in this instance. – JasonTerhorst

… Also, I did some further research, and noticed that Aaron Hillegass’ example on NSTimer (“TypingTutor”) exhibits this same behavior, which isn’t good in that case, either. Surely there is a workaround? Should I read on NSThread, or is that not useful? I’m using code from Apple’s QuartzComposerTexture example, which uses an NSTimer to render the view.

Timers fire only in certain specified runloop modes - NSDefaultRunLoopMode is the only one used if you’re using the scheduledTimer.. method. When a menu is down, there’s a pretty good chance that the runloop is running in NSEventTrackingRunLoopMode. You’ll probably find the same behavior for things like dragging a slider’s knob.

Solution: don’t use the scheduledTimer.. methods. Create your timer with timerWithTimeInterval.. and then use -[NSRunLoop addTimer:forMode:] to add it to the run loop in whatever modes you’re interested in (probably default, modal and event tracking, sounds like).

Yeah, actually, I just found info that fixed the problem at This little code snippet did it:

NSRunLoop currentRunLoop] addTimer:_renderTimer forMode:NSEventTrackingRunLoopMode];

I needed the scheduledTimer in this case, since it wasn’t working with the other types of methods. But, no matter, since [[NSRunLoop will take it without complaint anyway.