truongvinht

- (void)viewDidLoad {
  [super viewDidLoad];

  UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  [button setTitle:@"BUTTON" forState:UIControlStateNormal];
  [button setFrame:CGRectMake(50, 50, 150, 150)];
  
  [self.view addSubview:button];
  
  UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(invokePanGesture:)];