iOS实现垂直滑动条效果

我们知道在 iOS 开发中，有一个控件经常用到，那就是滑动条（UISlider），可以满足我们滑动取值的需求。但是现在有一个需求，就是需要一个垂直的滑动条，而 UISlider 并不能设置为垂直滑动，所以我们就需要自己定义一个控件来实现垂直的要求。

整理之后，我们可以得出需要以下的基本需求：

• 可以上下滑动
• 按钮可以自定义图片
• 可以设置最小值
• 可以设置最大值
• 可以在滑动过程中获取实时的值
• 可以在滑动结束时获取到最终的值
• 可以设置进度背景色

我们的实现原理就是实现一个自定义的 UIView，然后在上面添加需要用到的控件，对控件添加一定的手势功能，从而实现垂直滑动。实现了一个单独的类，功能不多，但是能满足以上基本的需求，代码如下，代码中用到的宏可以自行替换，开箱即用，简单明了：

VerticalSlider.h

//
//  VerticalSlider.h
//  
//
//  Created by huang zhengguo on 2019/8/30.
//  Copyright  2019 huang zhengguo . All rights reserved.
//
 
#import <UIKit/UIKit.h>
 
NS_ASSUME_NONNULL_BEGIN
 
@interface VerticalSlider : UIView
 
@property (assign, nonatomic) float value;
@property (strong, nonatomic) UIImage *thumImage;
@property (assign, nonatomic) float minimumValue;
@property (assign, nonatomic) float maximumValue;
 
@property (copy, nonatomic) void (^passValue) (float);
@property (copy, nonatomic) void (^passEndValue) (float);
 
/**
 * 初始化滑动条
 *
 * @param frame 大小
 * @param title 标题
 * @param progressColor 进度颜色
 * @param thumImage 滑动按钮背景
 *
 * @return 垂直滑动条
 *
 */
- (instancetype)initWithFrame:(CGRect)frame title:(NSString *)title progressColor:(UIColor *)progressColor thumImage:(NSString *)thumImage;
 
@end
 
NS_ASSUME_NONNULL_END

VerticalSlider.m

//
//  VerticalSlider.m
// 
//
//  Created by huang zhengguo on 2019/8/30.
//  Copyright  2019 zhengguohuang. All rights reserved.
//
 
#import "VerticalSlider.h"
 
#define THUM_BTN_WIDTH 30.0
#define THUM_BTN_HEIGHT 50.0
 
@interface VerticalSlider()
 
@property (strong, nonatomic) UIButton *thumBtn;
// 使用两个label表示进度，一个背景，一个进度
@property (strong, nonatomic) UILabel *backLabel;
@property (strong, nonatomic) UILabel *progressLabel;
// 底部标题
@property (strong, nonatomic) UILabel *titleLabel;
// 值标题
@property (strong, nonatomic) UILabel *valueLabel;
 
@end
 
@implementation VerticalSlider
 
- (instancetype)initWithFrame:(CGRect)frame title:(NSString *)title progressColor:(UIColor *)progressColor thumImage:(NSString *)thumImage {
    if (self = [super initWithFrame:frame]) {
        // 滑动按钮
        self.thumBtn = [[UIButton alloc] init];
 
        [self.thumBtn setBackgroundImage:[UIImage imageNamed:thumImage] forState:UIControlStateNormal];
        self.thumBtn.translatesAutoresizingMaskIntoConstraints = NO;
        
        UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(thumbPanAction:)];
 
        [self.thumBtn addGestureRecognizer:panGestureRecognizer];
        [self addSubview:self.thumBtn];
 
        // 进度条
        self.backLabel = [[UILabel alloc] init];
 
        self.backLabel.backgroundColor = [progressColor colorWithAlphaComponent:0.3];
        self.backLabel.translatesAutoresizingMaskIntoConstraints = NO;
 
        [self addSubview:self.backLabel];
 
        self.progressLabel = [[UILabel alloc] init];
 
        self.progressLabel.backgroundColor = progressColor;
        self.progressLabel.translatesAutoresizingMaskIntoConstraints = NO;
 
        [self addSubview:self.progressLabel];
 
        // 底部标题
        self.titleLabel = [[UILabel alloc] init];
 
        self.titleLabel.translatesAutoresizingMaskIntoConstraints = NO;
        self.titleLabel.textAlignment = NSTextAlignmentCenter;
        self.titleLabel.textColor = [UIColor whiteColor];
        self.titleLabel.text = title;
 
        [self addSubview:self.titleLabel];
 
        // 顶部值
        self.valueLabel = [[UILabel alloc] init];
 
        self.valueLabel.translatesAutoresizingMaskIntoConstraints = NO;
        self.valueLabel.textAlignment = NSTextAlignmentCenter;
        self.valueLabel.textColor = [UIColor whiteColor];
 
        [self addSubview:self.valueLabel];
 
        [self bringSubviewToFront:self.thumBtn];
 
        [self setConstraints];
        
        // 初始化数据
        self.value = 0.0;
    }
    
    return self;
}
 
#pragma mark --- 按钮拖动方法
- (void)thumbPanAction:(UIPanGestureRecognizer *)panGestureRecognizer {
    // 转换坐标
    CGPoint point = [panGestureRecognizer translationInView:self];
    
    CGFloat yOriginPoint = panGestureRecognizer.view.frame.origin.y + point.y;
    if (yOriginPoint >=self.backLabel.frame.origin.y && yOriginPoint <= (self.backLabel.frame.origin.y + self.backLabel.frame.size.height - THUM_BTN_HEIGHT)) {
        panGestureRecognizer.view.frame = CGRectMake(panGestureRecognizer.view.frame.origin.x, panGestureRecognizer.view.frame.origin.y + point.y, THUM_BTN_WIDTH, THUM_BTN_HEIGHT);
        
        self.value = 1.0 - (yOriginPoint - self.backLabel.frame.origin.y) / (self.backLabel.frame.size.height - THUM_BTN_HEIGHT);
        if (self.passValue) {
            KMYLOG(@"colorValue = %f", self.value);
            self.passValue(self.value);
        }
    }
 
    // 转换成原来坐标系的坐标
    [panGestureRecognizer setTranslation:CGPointMake(0, 0) inView:self];
    
    if (panGestureRecognizer.state == UIGestureRecognizerStateEnded) {
        if (self.passEndValue) {
            KMYLOG(@"结束滑动");
            // 转为字符串，又转为float，是为了去的两位小数的浮点数
            self.passEndValue([[NSString stringWithFormat:@"%.2f", self.value] floatValue]);
        }
    }
}
 
- (void)setValue:(float)value {
    _value = value;
 
    self.thumBtn.frame = CGRectMake(self.thumBtn.frame.origin.x, (self.backLabel.frame.size.height - THUM_BTN_HEIGHT) * (1 - value) + self.backLabel.frame.origin.y, THUM_BTN_WIDTH, THUM_BTN_HEIGHT);
    self.progressLabel.frame = CGRectMake(self.progressLabel.frame.origin.x, self.thumBtn.frame.origin.y + THUM_BTN_HEIGHT, self.progressLabel.frame.size.width, self.backLabel.frame.origin.y + self.backLabel.frame.size.height - self.thumBtn.frame.origin.y - THUM_BTN_HEIGHT);
    self.valueLabel.text = [NSString stringWithFormat:@"%.0f%%", value * 100];
}
 
- (void)setConstraints {
    NSArray *titleLabelArray = @[self.titleLabel, self.valueLabel];
    for (UILabel *label in titleLabelArray) {
        NSLayoutConstraint *labelLeadingLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeLeading multiplier:1.0 constant:0.0];
        NSLayoutConstraint *labelTrailingLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:0.0];
        NSLayoutConstraint *labelHeightLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:30.0];
 
        [self addConstraints:@[labelLeadingLayoutConstraint, labelTrailingLayoutConstraint, labelHeightLayoutConstraint]];
 
        if (label == self.titleLabel) {
            NSLayoutConstraint *labelBottomLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0.0];
 
            [self addConstraint:labelBottomLayoutConstraint];
        } else if (label == self.valueLabel) {
            NSLayoutConstraint *labelTopLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeTop multiplier:1.0 constant:0.0];
 
            [self addConstraint:labelTopLayoutConstraint];
        }
    }
    
    NSArray *labelArray = @[self.backLabel, self.progressLabel];
    for (UILabel *label in labelArray) {
        NSLayoutConstraint *progressCenterXLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0];
        NSLayoutConstraint *progressBottomLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.titleLabel attribute:NSLayoutAttributeTop multiplier:1.0 constant:-8.0];
        NSLayoutConstraint *progressWidthLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:3.0];
 
        [self addConstraints:@[progressCenterXLayoutConstraint, progressBottomLayoutConstraint, progressWidthLayoutConstraint]];
 
        if (label == self.backLabel) {
            NSLayoutConstraint *progressTopLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.valueLabel attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0.0];
 
            [self addConstraint:progressTopLayoutConstraint];
        } else {
            NSLayoutConstraint *progressHeightLayoutConstraint = [NSLayoutConstraint constraintWithItem:label attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:0.0];
 
            [self addConstraint:progressHeightLayoutConstraint];
        }
    }
 
    NSLayoutConstraint *thumBtnCenterXLayoutConstraint = [NSLayoutConstraint constraintWithItem:self.thumBtn attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0];
    NSLayoutConstraint *thumBtnBottomLayoutConstraint = [NSLayoutConstraint constraintWithItem:self.thumBtn attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self.backLabel attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0.0];
    NSLayoutConstraint *thumBtnWidthLayoutConstraint = [NSLayoutConstraint constraintWithItem:self.thumBtn attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:THUM_BTN_WIDTH];
    NSLayoutConstraint *thumBtnHeightLayoutConstraint = [NSLayoutConstraint constraintWithItem:self.thumBtn attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:THUM_BTN_HEIGHT];
 
    [self addConstraints:@[thumBtnCenterXLayoutConstraint, thumBtnBottomLayoutConstraint, thumBtnWidthLayoutConstraint, thumBtnHeightLayoutConstraint]];
}
 
- (void)layoutSubviews {
    [super layoutSubviews];
    
    self.thumBtn.frame = CGRectMake(self.thumBtn.frame.origin.x, (self.backLabel.frame.size.height - THUM_BTN_HEIGHT) * (1 - self.value) + self.backLabel.frame.origin.y, THUM_BTN_WIDTH, THUM_BTN_HEIGHT);
    self.progressLabel.frame = CGRectMake(self.progressLabel.frame.origin.x, self.thumBtn.frame.origin.y + THUM_BTN_HEIGHT, self.progressLabel.frame.size.width, self.backLabel.frame.origin.y + self.backLabel.frame.size.height - self.thumBtn.frame.origin.y - THUM_BTN_HEIGHT);
}
 
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
}
*/
 
@end

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