iphone - 实现步骤/捕捉 UISlider

Question

我正在尝试使用 UISlider 实现某种形式的捕捉或步骤。我编写了以下代码，但它并没有像我希望的那样顺利。它可以工作，但是当我向上滑动它时，它会向右移动 5 个点，使手指不在“滑动圆”的中心

这是我的代码，其中 self.lastQuestionSliderValue 是我已将其设置为 slider 初始值的类的属性。

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

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

Answer 1

这实际上比我最初想象的要容易得多。最初我试图获得拇指矩形属性并进行复杂的数学运算。这是我最终得到的结果:

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;
}

确保您连接了 UISlider View 的方法和 socket ，然后就可以开始了。