hello.mm

// Header

@interface AnOperation : NSOperation
@property (nonatomic, readonly) NSString *ifa;
@property (nonatomic, assign) double timeInterval;
@end

// .m
// Tries to access a property with an exponential back-off

@implementation AnIFAOperation

- (void)main
{
	_timeInterval = 0.0;
	[NSTimer scheduledTimerWithTimeInterval:_timeInterval
									 target:self
								   selector:@selector(startWithTimer:)
								   userInfo:nil
									repeats:NO];
    [[NSRunLoop currentRunLoop] run];
}

- (BOOL)isExecuting
{
	if (!_ifa) {
		return YES;
	}
	
	return NO;
}

- (BOOL)isFinished
{
	if (!_ifa) {
		return NO;
	}
	
	return YES;
}

- (NSString *)getIFA
{
	return [[ASIdentifierManager sharedManager].advertisingIdentifier UUIDString];
}

-(void)startWithTimer:(NSTimer *)timer
{
	if (!_ifa) {
		_ifa = [self getIFA];
		
		if (!_ifa) {
			_timeInterval = _timeInterval >= 1.0 ? _timeInterval * 2.0 : 1.0;
			_timeInterval = MIN(60.0, _timeInterval);
			[NSTimer scheduledTimerWithTimeInterval:_timeInterval
											 target:self
										   selector:@selector(startWithTimer:)
										   userInfo:nil
											repeats:NO];
		}
		[timer invalidate];
	}
}

@end