macOS sleep() VS. usleep() VS. [NSThread sleepForTimeInterval:]

[Darkroom]

i don't really understand the difference between these 3 functions... assuming i have a program running, with several timers going on in the background for different things, and i execute an IBAction which would execute some stuff and then pause for 2 seconds before redirecting to another method in the class... which of these 3 functions are better to use and why?

-(IBAction)start:(id)sender
{
[COLOR="Green"]//do something;
//do something else;[/COLOR]

[NSThread sleepForTimeInterval:2]; [COLOR="green"]//or[/COLOR]
sleep(2); [COLOR="green"]//or[/COLOR]
usleep(2000);

[COLOR="green"]//then redirect to another method within the class[/COLOR]
}

i should probably mention that while "usleep" seems to be an actual function and compiles without error: usleep(<#useconds_t #>), it doesn't work for me at all...

 

[kpua]

They're essentially all wrappers around nanosleep() and just provide different conveniences.

I think useconds_t is just a typedef for unsigned long or unsigned long long, so passing other integer types won't cause errors.


Haha... sorry. I didn't see the actual question in there—it was too early in the morning. Do what Catfish Man said.

 

[Catfish_Man]

None of the above. Sleeping the main thread will just lag your program. Instead, schedule an NSTimer to fire two seconds later with the work you need done.

 

[iSee]

i should probably mention that while "usleep" seems to be an actual function and compiles without error: usleep(<#useconds_t #>), it doesn't work for me at all...

The parameter of usleep() is in microseconds. That's millionths of a second. So usleep(2000) will sleep for 2 milliseconds (two thousandths of a second)--too fast for a human to perceive. sleep(2) would be equivalent to usleep(2000000).

 

[Darkroom]

The parameter of usleep() is in microseconds. That's millionths of a second. So usleep(2000) will sleep for 2 milliseconds (two thousandths of a second)--too fast for a human to perceive. sleep(2) would be equivalent to usleep(2000000).

ooohhhh! i though it was just my lefts and rights that i got mixed up, now i've got to deal with microseconds and milliseconds too ... but at least now i know why it wasn't working... thanks for that...

 

[Darkroom]

i had noticed that [NSThread sleepForTimeInterval:2]; actually pauses my application instead of just the class it's in, which i had assumed the later would be the case...

after playing around with this function, i had noticed that the spinning beachball would show up if i set it this function to around 5 seconds... strange? yes/no?

i've therefore decided to use [NSThread sleepForTimeInterval:0.5]; instead of using NSTimer - simply because NSTimer gave unexpected/unwanted results in certain situations.

 

[lee1210]

Catfish_Man warned about this behavior above. I would look into NSTimer as be suggested.

-Lee