GCDRetainCycle4.m

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.proArray = [[NSMutableArray alloc]init];
    
    GCDVC2* __weak weakSelf = self;

    self.postGCDBlock = ^{

        [weakSelf.proArray removeObject:@"3"];
        NSLog(@"%@",weakSelf.proArray);
        [weakSelf.activityIndicator stopAnimating];
    };
    
    self.addObjectsBlock = ^{

        [weakSelf.proArray addObject:@"2"];
        [weakSelf.proArray addObject:@"3"];
        [NSThread sleepForTimeInterval:10];
        
        dispatch_async(dispatch_get_main_queue(),weakSelf.postGCDBlock);
    };
}