- (void)viewDidLoad
{
    [super viewDidLoad];
	
    NSDate *now = [NSDate date];
    
    dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
	dispatch_group_t g = dispatch_group_create();
	dispatch_semaphore_t semaphore = dispatch_semaphore_create(1);//同期処理の個数を書く。2つの処理を同時に行う場合は１
    
	dispatch_group_async(g,q,^{
		
        int i = 0;
        while(i < 100){
            NSLog(@"%d",i);
            i++;
        }
        
		dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
		dispatch_semaphore_signal(semaphore);
	});
	dispatch_group_async(g,q,^{
        
        int i = 0;
        while(i < 100){
            NSLog(@"%@",@"----------------------------------");
            i++;
        }
        
		dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
		dispatch_semaphore_signal(semaphore);
	});
    
    
    
	dispatch_group_wait(g, DISPATCH_TIME_FOREVER);
    
    NSDate *then = [NSDate date];
 
    NSLog(@"then - now: %1.3fsec",[then timeIntervalSinceDate:now]);
	printf("end");
}