限制滑动UISlider超过某一点 [英] Limit sliding UISlider past certain point

问题描述

我们假设有一个 UISlider ，我设置了一个特定的值。然后滑块手柄移动到该值，如预期的那样。

Let's assume a have a UISlider to which I set a certain value. The slider handle then moves to that value, as expected.

现在我想让用户来回滑动滑块的手柄，但是不要设置 UISlider的值比我以编程方式分配的更少。

Now I want to let the user slide the handle of the slider back and forth, but to not set the value of the UISlider to be less, than I assigned to it programmatically.

所以例如我有一个 UISlider 最小值为0，最大值为100，我将其值设置为50.我不希望用户滑动lefter而不是50但是在右侧我想让用户滑动来回处理。

So for example I have a UISlider with a min value of 0 and a max value of 100 and I set its value to be 50. I don't want the user to slide "lefter" than 50 but on the "right" of it I want to let the user slide the handle back and forth.

如何在Obj-C中实现这种行为？

How do you implement this sort of behaviour in Obj-C?

推荐答案

您应首先确保连续发送更新事件：

You should first make sure the updates event are sent continuously:

mySlider.continuous = YES;

您也可以在故事板/笔尖中执行此操作（由@fDmitry提及，这是默认值IB中的状态。

You can also do that in your storyboard/nib (as mentionned by @fDmitry, this is the default state in IB).

然后你必须将你的滑块链接到.h文件中的 IBAction （创建通过ctrl-从IB拖动到您的代码的链接），并将其分配给滑块的Value Changed事件。这将创建一个这样的方法：

Then you have to link your slider to an IBAction in your .h file (create a link by ctrl-dragging from IB to your code), and assign it to the "Value Changed" event of your slider. This will create a method like this:

-(IBAction)sliderValueChanged:(id)sender;

以这种方式实施：

- (IBAction)sliderValueChanged:(id)sender {

    float maxValue = 50.0f;

    if ([(UISlider*)sender value] > maxValue) {
        [(UISlider*)sender setValue:maxValue];
    }
}

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