UIScrollView pauses NSTimer until scrolling finishes

While a UIScrollView (or a derived class thereof) is scrolling, it seems like all the NSTimers that are running get paused until the scroll is finished.

--

You have to run another thread and another run loop if you want timers to fire while scrolling; since timers are processed as part of the event loop, if you're busy processing scrolling your view, you never get around to the timers. Though the perf/battery penalty of running timers on other threads might not be worth handling this case.

 

An easy & simple to implement solution is to do:

NSTimer *timer = [NSTimer timerWithTimeInterval:... 
                                         target:...
                                       selector:....
                                       userInfo:...
                                        repeats:...];
[[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];