Delay AND Sleep

Delay:

 [self performSelector:@selector(pushView) withObject:nil afterDelay:1.0];

- (void) pushView {

        [self.navigationController popViewControllerAnimated:YES];

}

Sleep:

sleep(1);

Perform action after time while user is interacting:

double delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    <#code to be executed on the main queue after delay#>

});

eg:

-(void)aMethod:(UIButton *)sender{

NSLog(@"Before");

    double delayInSeconds = 2.0;

    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));

    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

NSLog(@"after 2");

      });

}