Creating a timer with Grand Central Dispatch - Make Sure It Runs !

Timer with Grand Central Dispatch

#define TIME_INTERVAL_TO_FIRE 15 * NSEC_PER_SEC

#import <Foundation/Foundation.h>

@interface SampleClass : NSObject
{
  dispatch_source_t timer;
}

- (void)startTimer;
- (void)cancelTimer;

@end


#import "SampleClass.h"


@implementation SampleClass {
    dispatch_source_t _timer;
}

- (void)startTimer
{
        dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0);
        timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
        dispatch_source_set_timer(timer, DISPATCH_TIME_NOW,TIME_INTERVAL_TO_FIRE , (1ul * NSEC_PER_SEC)/10);
        dispatch_source_set_event_handler(timer, ^
                                          {
                                              //do something
                                          });
        
        
        dispatch_resume(timer);

    
}

- (void)cancelTimer
{
    if (timer) {
        dispatch_source_cancel(timer);
        timer = nil;
    }
}

@end