- (UIButton *)panButton { if (!_panButton) {  UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panAction:)];  _panButton = [[UIButton alloc] init];  _panButton.backgroundColor = [UIColor blueColor];  _panButton.layer.borderWidth = 1.f;  _panButton.layer.borderColor = [UIColor greenColor].CGColor;  [_panButton setTitle:@"清除緩存" forState:UIControlStateNormal];  _panButton.titleLabel.font = [UIFont systemFontOfSize:9];  [_panButton addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];  [_panButton addGestureRecognizer:panGesture]; } return _panButton;}- (void)panAction:(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];}-(void)buttonAction:(UIButton *)sender{ NSLog(@"煩人，點我干啥~");}