实现步骤/捕捉UISlider [英] Implementing steps/snapping UISlider

问题描述

我正在尝试使用UISlider实现某种形式的捕捉或步骤。我写了下面的代码，但它没有像我希望的那样顺利。它可以正常工作，但是当我向上滑动时，它会向右滑动5个点，手指不会在滑动圆圈上方居中

I am trying to implement some form of snapping or steps with the UISlider. I have written the following code but it does not work as smooth as I hoped for. It works, but when the I slide it upwards it snap 5points to the right leaving the finger not centered over the "slide-circle"

这是我的代码，其中 self.lastQuestionSliderValue 是我设置为滑块初始值的类的属性。

This is my code where self.lastQuestionSliderValue is a property of the class which I have set to the initial value of the slider.

    if (self.questionSlider.value > self.lastQuestionSliderValue) {
        self.questionSlider.value += 5.0;
    } else {
        self.questionSlider.value -= 5.0;
    }

    self.lastQuestionSliderValue = (int)self.questionSlider.value;

推荐答案

这实际上比我想象的要容易得多。最初我试图获得正确的属性并做复杂的数学运算。以下是我最终的结果：

It's actually considerably easier than I first thought. Originally I was trying to get the thumbrect property and do complicated math. Here's what I ended up with:

h文件：

@property (nonatomic, retain) IBOutlet UISlider* questionSlider;
@property (nonatomic) float lastQuestionStep;
@property (nonatomic) float stepValue;

m文件：

- (void)viewDidLoad {
    [super viewDidLoad];

    // Set the step to whatever you want. Make sure the step value makes sense
    //   when compared to the min/max values for the slider. You could take this
    //   example a step further and instead use a variable for the number of
    //   steps you wanted.
    self.stepValue = 25.0f;

    // Set the initial value to prevent any weird inconsistencies.
    self.lastQuestionStep = (self.questionSlider.value) / self.stepValue;
}

// This is the "valueChanged" method for the UISlider. Hook this up in
//   Interface Builder.
-(IBAction)valueChanged:(id)sender {
    // This determines which "step" the slider should be on. Here we're taking 
    //   the current position of the slider and dividing by the `self.stepValue`
    //   to determine approximately which step we are on. Then we round to get to
    //   find which step we are closest to.
    float newStep = roundf((questionSlider.value) / self.stepValue);

    // Convert "steps" back to the context of the sliders values.
    self.questionSlider.value = newStep * self.stepValue;
}

确保您连接UISlider视图的方法和插座应该不错。

Make sure you hook up the method and the outlet for your UISlider view and you should be good to go.

这篇关于实现步骤/捕捉UISlider的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！