Idle thread approach in iOS

Question

I'm trying to set up a thread that stays idle until new data it's available. What it's the best approach for this in Objective-C? Till now I tried to make a simple run loop

while(YES) {
   if(isDataAvailable) {
      //process data
   }
}

However this has an huge impact on performance, my FPS drops from 40 to 20 and the interface becomes unusable (even if the actual data process happens once in a second or so and it's not very intense for the CPU. I tried to add [NSThread sleepForTimeInterval:0.01] at the end, but this way I lose data packages ('process data' refers to some streaming related operations, queue and unqueue data packages), however the FPS returns to normal.

I'm fair new in Objective-C and I was thinking maybe there is a better way to do this? I also had a look over NSRunLoop, but didn't manage to make it work as a run loop :), only attached a timer to it that doesn't do more than my [NSThread sleepForTimeInterval:0.01] thing.

Any help it's highly appreciated:D

Answer 1

If you need to keep the seconary thread alive, you definitely want to use a real runloop: http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Multithreading/RunLoopManagement/RunLoopManagement.html#//apple_ref/doc/uid/10000057i-CH16-SW1

Basically, just create and start your thread, set up an autorelease pool, then run your runloop for some set time amount. When the time expires, you check to see if you should exit your thread, or enter into the runloop again.

As Marcelo points out though, there are more modern approaches to achieve concurrency (GCD and async dispatch being a couple of examples) so maybe investigate other forms of concurrency as well.