SheldonWangRJT/sleep_in_ios.md

## sleep_in_ios.md

      
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              sleep_in_ios.md
            
          
    #iOSBySheldon #objective-c #swift #unitTest #uiTest #sleep
This notes is written by Sheldon. You can find me with #iOSBySheldon in Github, Youtube, Facebook, etc.
The only reason that I wrote this short quick note is that, the answers on the internet is somewhat misleading.
If we are running sleep() usleep() or [NSThread sleepForTimeInterval:] in your main app, there should not be any difference. Because the first two functions are just functions that from c and the third one is from objective-c.
However,

You probably should NOT call them in your main app, because for delay operations you should more use (in Swift)
swift DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(4), execute: { // Put your code which should be executed with a delay here }) 
If you are using these functions in tests (Unit test & UI automation Test), they are slightly different. In my observation, calling sleep() will pause the operation (tap, swipe), [NSThread sleepForTimeInterval:] will likely pause the app execution.

Summary

Trying all of the three in your code, specially in testing classes, if one is not working. They are not quite same.