在UISlider的拇指图像上连续更改UILabel的值

问题描述

我有 UISlider （最小1，最大10）。我希望它的拇指放置在它上面的 UILabel ，在移动 UISlider 时不断更新和更改其文本的拇指。所以，我从 UISlider 中抓取了拇指图像，并向其添加了 UILabel ，但标签似乎覆盖了自己而没有删除移动拇指后的前一个值。

I have a UISlider(min 1 ,max 10). I want its thumb to have a UILabel placed on top of it that continuously updates and changes its text on moving the UISlider's thumb. So, I grabbed thumb image from the UISlider and added a UILabel to it but the label seems to overwrite itself without erasing the previous value once the thumb is moved.

- (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，

Then, when i start dragging,

我希望标签擦除之前的值，并在移动拇指时显示当前值。感谢任何帮助。谢谢！

I want the label to erase the previous value and show current value as the thumb is moved. Any help is appreciated.Thanks!

推荐答案

您的代码会不断添加新的子视图。删除现有的子视图：

Your code continuously adds new subviews. Remove the existing subviews with:

[handleView.subviews makeObjectsPerformSelector:@(removeFromSuperview)];

或者，重复使用现有标签。也许使用标签和 viewWithTag：来查找现有标签和更新（或创建，如果没有找到）。重用比娱乐更有效。

Alternatively, reuse the existing label. Perhaps using a tag and viewWithTag: to find the existing label and update (or create if not found). Reuse is more efficient than recreation.

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