连续改变 UISlider 拇指图像上 UILabel 的值

我有一个UISlider（最少 1 个，最多 10 个）。我希望它的拇指有一个UILabel放置在它的顶部，在移动时不断更新和更改其文本UISlider的拇指。所以，我从UISlider并添加了一个UILabel但一旦拇指移动，标签似乎会覆盖自身，而不会删除以前的值。

- (IBAction)SnoozeSliderValueChanged:(id)sender {

    UIImageView *handleView = [_snoozeSlider.subviews lastObject];
    UILabel *label = [[UILabel alloc] initWithFrame:handleView.bounds];
    label.text = [NSString stringWithFormat:@"%0.0f", self.snoozeSlider.value];
    label.backgroundColor = [UIColor clearColor];
    label.textAlignment = NSTextAlignmentCenter;
    [handleView addSubview:label];

}

最初，

然后，当我开始拖动时，

我希望标签在拇指移动时擦除以前的值并显示当前值。如有任何帮助，我们将不胜感激。谢谢！

    - (IBAction)SnoozeSliderValueChanged:(id)sender {

        //Get the Image View
        UIImageView *handleView = [_snoozeSlider.subviews lastObject];

        // Get the Slider value label
        UILabel *label = (UILabel*)[handleView viewWithTag:1000];

        // If the slider label not exist then create it and add it to the Handleview. So handle view will have only one slider value label, so no more memory issues & not needed to remove from superview.
        // Creation of object is Pain to iOS. So simply reuse it by creating only once.
        // Note that tag setting below, which will helpful to find out that view presents in later case
        if (label==nil) {

            label = [[UILabel alloc] initWithFrame:handleView.bounds];

            label.tag = 1000;

            label.backgroundColor = [UIColor clearColor];

            label.textAlignment = NSTextAlignmentCenter;

            [handleView addSubview:label];


        }

        // Update the slider value
        label.text = [NSString stringWithFormat:@"%0.0f", self.snoozeSlider.value];

    }