View Full Version : sleep() question

Dec 10, 2008, 02:32 PM
I'm trying to write a script that will update an image then pause or sleep for 2 seconds and then set a different image.

Currently I'm using sleep(2). But it sleeps first and then updates the images after. I want to update first then pause then update again. Any help would be nice. Thanks

Dec 10, 2008, 03:53 PM
Any sleep() or delay inside the main thread blocks all UI activity, including pending display updates. Thus, it's the wrong paradigm for Cocoa. Don't do it.

Instead, learn to use NSTimers to call your methods, and let these methods do what you want to do at any point in time in the future. You may have to save the state of what you want to do next or later in static, global, or object variables, but that's a trivial problem for the student.

The only time this may be difficult is inside deeply recursive routines. You may want to run those in a background (non UI) thread instead.


Dec 10, 2008, 04:04 PM
Thanks for the reply. Can you give me an example of how I could us an NSTimer to delay or pause for 2 seconds? I'm new to xcode/cocoa and I'm not sure how to accomplish this. Thanks for the help.

Dec 10, 2008, 04:39 PM
Google turned up this:


and several other examples. YMMV.

There's also tons of documentation on Objective C, Cocoa and NSTimers on Apple's dev site.


Dec 10, 2008, 08:40 PM
Works great! Thanks!!