iOS 实现可拖动button

- (void)Action:(UIPanGestureRecognizer *)recognizer {
    CGPoint translationPoint = [recognizer translationInView:self.view];
    CGPoint center = recognizer.view.center;
    recognizer.view.center = CGPointMake(center.x + translationPoint.x, center.y + translationPoint.y);
    [recognizer setTranslation:CGPointZero inView:self.view];
}

UIPanGestureRecognizer* ges = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(Action:)];
    gesture.minimumNumberOfTouches = 1;
    gesture.maximumNumberOfTouches = 1;
    [btn addGestureRecognizer:ges];