Objective-C, running NSTask in background periodically

Question

I've seen some good information on how to keep an NSTask running in the background, although that's not entirely what I want to do. What I would like to do is periodically run an NSTask in the the background (like every 30 seconds), then kill it; here might be one example of what I would like to do:

NSTask *theTask = [ [ NSTask alloc ] init ];
NSPipe *taskPipe = [ [ NSPipe alloc ] init ];

[ theTask setStandardError:taskPipe ];
[ theTask setStandardOutput:taskPipe ];
[ theTask setLaunchPath:@"/bin/ls" ];
[ theTask setArguments:[ NSArray arrayWithObject:@"-l" ] ];
[ theTask launch ];

// Wait 30 seconds, then repeat the task

aleroot · Answer 1 · 2012-09-09T09:15:02.210

3

Maybe you can simply put in sleep the thread and wait 30 seconds inside a do loop :

do {

[ theTask launch ]; //Launch the Task
sleep(30);          //Sleep/wait 30 seconds 

} while (someCondition);

Otherwise you could use an NSTimer :

NSTimer *t = [NSTimer scheduledTimerWithTimeInterval: 30.0
                      target: self
                      selector:@selector(onTick:)
                      userInfo: nil repeats:YES];


- (void)onTick:(NSTimer *)timer {
    //In this method that will be get called each 30 seconds, 
    //you have to put the action that you want to perform ...
    [ theTask launch ];
}

edited Sep 09 '12 at 09:15

answered Sep 09 '12 at 09:08

aleroot

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1

That first approach is simply insupportable. I'm gonna give you +1 if you remove it. – Sep 09 '12 at 09:12
1

I think the answer to my question is here: http://stackoverflow.com/questions/1449035/how-do-i-use-nstimer – Joe Habadas Sep 09 '12 at 23:55
9 years later still getting upvotes for the NSTimer code! – spartygw Feb 22 '21 at 16:48

Objective-C, running NSTask in background periodically

1 Answers1