Movable Button on iOS

button.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.btn.frame = CGRectMake(10, 10, 50, 50);
    [self.btn setTitle:@"Touch" forState:UIControlStateNormal];
    [self.btn addTarget:self action:@selector(dragMoving:withEvent:) forControlEvents:UIControlEventTouchDragInside];
    [self.btn addTarget:self action:@selector(dragEnded:withEvent:) forControlEvents:UIControlEventTouchUpInside | UIControlEventTouchUpOutside];
    
    [self.view addSubview:self.btn];
}

- (void) dragMoving: (UIControl *) c withEvent:ev
{
    c.center = [[[ev allTouches] anyObject] locationInView:self.view];
}

- (void) dragEnded: (UIControl *) c withEvent:ev
{
    c.center = [[[ev allTouches] anyObject] locationInView:self.view];
}