效果圖如下：

拖動按鈕.png

實現(xiàn)方案

1、采用系統(tǒng)UISlider實現(xiàn)
2奔浅、自己使用貝塞爾曲線繪制

方案一（不可行馆纳，有bug）

遇到的問題：當將UISlider的寬度加寬的一定寬度后，拖動效果不是漸變汹桦，會突然發(fā)送改變鲁驶，此處簡單記錄下UISlider的基礎用法
1、基礎設置

// 初始化
UISlider *slider = [[UISlider alloc] initWithFrame:CGRectMake(100, 200, 100, 20)];  
// 添加到俯視圖
[self.view addSubview:slider]; 

// 設置最小值
slider.minimumValue = 9;  
// 設置最大值
slider.maximumValue = 11;  
// 設置初始值  
 slider.value = (slider.minimumValue + slider.maximumValue) / 2;
// 設置可連續(xù)變化
 slider.continuous = YES;  
//滑輪左邊顏色舞骆，如果設置了左邊的圖片就不會顯示  
slider.minimumTrackTintColor = [UIColor greenColor]; 
//滑輪右邊顏色钥弯，如果設置了右邊的圖片就不會顯示  
slider.maximumTrackTintColor = [UIColor redColor];
 
/// 也可設置為圖片
///[slider setMinimumTrackImage:[UIImageimageNamed:@"max.png"] forState:UIControlStateNormal];
//[slider setMaximumTrackImage:[UIImageimageNamed:@"min.png"] forState:UIControlStateNormal];
 
//設置了滑輪的顏色，如果設置了滑輪的樣式圖片就不會顯示  slider.thumbTintColor = [UIColor redColor];
// 針對值變化添加響應方法  
 [slider addTarget:self action:@selector(sliderValueChanged:) forControlEvents:UIControlEventValueChanged];

2督禽、旋轉(zhuǎn)90度脆霎，豎直放置

slider.transform = CGAffineTransformMakeRotation(1.57079633);

3、改變slider的寬度（方法3）狈惫，需要重寫一個繼承與UISlider的類了,然后重寫里面的實現(xiàn)方法來控制:

/// 設置最小值
- (CGRect)minimumValueImageRectForBounds:(CGRect)bounds;
/// 設置最大值
- (CGRect)maximumValueImageRectForBounds:(CGRect)bounds;
/// 控制slider的寬高
- (CGRect)trackRectForBounds:(CGRect)bounds;
/// 改變滑塊的觸摸范圍
- (CGRect)thumbRectForBounds:(CGRect)bounds trackRect:(CGRect)rect value:(float)value;

方案二（自己繪制）

提供實現(xiàn)代碼如下
.h文件

#import <UIKit/UIKit.h>

typedef void (^sliderBlock)(float);
NS_ASSUME_NONNULL_BEGIN

@interface HYLightSlider : UIView
@property (nonatomic, copy) sliderBlock clickBlock;
-(instancetype)initWithFrame:(CGRect)frame defaultValue:(float)defaultValue;
@end

NS_ASSUME_NONNULL_END

.m文件

#import "HYLightSlider.h"

@interface HYLightSlider()
@property (nonatomic, assign) float defaultValue;
@property (nonatomic, assign) float offSet;
@property (nonatomic, strong) UIBezierPath *path;
@property (nonatomic, strong) CAShapeLayer *tubeShape;
@end

@implementation HYLightSlider
-(instancetype)initWithFrame:(CGRect)frame defaultValue:(float)defaultValue{
    self = [super initWithFrame:frame];
    if(self){
        self.backgroundColor = [UIColor clearColor];
        self.defaultValue = defaultValue;
        UIPanGestureRecognizer *imageViewPanGesture = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panGesture:)];
        [self addGestureRecognizer:imageViewPanGesture];
        [self initNewPath];
        [self drawWholeShape];
    }
    return self;
}
- (void)initNewPath{
    self.path = [UIBezierPath bezierPath];
    self.tubeShape = [[CAShapeLayer alloc]init];
    self.tubeShape.strokeColor = [UIColor colorWithHexValue:HY_COR3].CGColor;
    self.tubeShape.fillColor = [UIColor colorWithHexValue:HY_COR3].CGColor;
}

- (void)drawWholeShape{
    // 管道
    for (CALayer *object in self.layer.sublayers) {
        [object removeFromSuperlayer];
    }
    [self.path removeAllPoints];
    self.path.lineWidth = self.frame.size.width;
    [self.path moveToPoint:CGPointMake(self.frame.size.width/2.0, self.frame.size.height)];
    [self.path addLineToPoint:CGPointMake(self.frame.size.width/2.0, self.frame.size.height*(1.0-self.defaultValue))];//添加一條子路徑
    [self.path stroke];
    self.tubeShape = [[CAShapeLayer alloc]init];
    self.tubeShape.path = self.path.CGPath;
    self.tubeShape.lineWidth = self.frame.size.width;

    self.tubeShape.strokeColor = [UIColor colorWithHexValue:HY_COR3].CGColor;
    self.tubeShape.fillColor = [UIColor colorWithHexValue:HY_COR3].CGColor;
    [self.layer addSublayer:self.tubeShape];
}
#pragma mark --- targetView的拖拽手勢
- (void)panGesture:(UIPanGestureRecognizer *)gesture{
    switch (gesture.state) {
        case UIGestureRecognizerStateBegan:
        {
            NSLog(@"滑動開始");
        }
            break;
        case UIGestureRecognizerStateChanged:
        {
            // 獲得添加手勢的對象
            // 獲得滑動的距離  包含 x y 移動的數(shù)值
            CGPoint point  =[gesture translationInView:gesture.view];
            //向下滑動
            if(point.y >= self.frame.size.height*self.defaultValue){
                self.offSet = self.frame.size.height*self.defaultValue;
            //向上滑動
            }else if(-point.y >= self.frame.size.height - self.frame.size.height*self.defaultValue){
                self.offSet = -self.frame.size.height + self.frame.size.height*self.defaultValue;
            }else{
                self.offSet = point.y;
            }
            self.offSet = self.offSet*0.1;
            self.defaultValue = (-self.offSet+self.frame.size.height*self.defaultValue)/self.frame.size.height;
            if(self.defaultValue < 0.0 || self.defaultValue > 1.0){
                return;
            }
            [self.tubeShape setNeedsDisplay];
            [self drawWholeShape];
            NSLog(@"滑動中");
            NSLog(@"%f",self.offSet);
        }
            break;
        case UIGestureRecognizerStateEnded:
        {
            NSLog(@"%f",self.offSet);
            NSLog(@"滑動結(jié)束");
            self.clickBlock ? self.clickBlock(self.defaultValue) : nil;
            
        }
            break;
        default:
            break;
    }
}

@end