GCD timer in a UIViewController

gistfile1.m

@interface MyViewController()
@property (nonatomic, assign) dispatch_source_t timer;
- (void)handleTimer;
@end

@implementation
@synthesize timer=timer_;

- (id)init {
	self = [super initWithNibName:NSStringFromClass([self class]) bundle:nil];
	if (self) {
		// Timer setup code:
		dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
		if (timer) {
			__block MyViewController *blockSelf = self;
			dispatch_source_set_event_handler(timer, ^{
				// This code is called by the timer
				[blockSelf handleTimer];
			});
			self.timer = timer;
		}
	}
	return self;
}

- (void)viewWillAppear {
	if (self.timer) {
		dispatch_resume(self.timer);
	}
}

- (void)viewWillDisapear

- (void)handleTimer {
	NSLog(@"Timer triggered");
}