IOS可以拖动的UIButton

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.btn.frame = CGRectMake(10, 10, 50, 50);

    [self.btn setTitle:@"触摸" forState:UIControlStateNormal];
    [self.btn setTitle:@"移动" forState:UIControlEventTouchDown];
    [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];
}