UISlider基本使用

UISlider是一个很常用的UI控件，调节屏幕亮度或者调节音量大小等很多地方都可以用到，而且使用方便，下面我来介绍一下UISlider的基本使用。

首先介绍一下基本属性和常用方法：

//设置当前slider的值，默认为0.0
@property(nonatomic) float value;
//设置slider的最小值 @property(nonatomic) float minimumValue; //设置slider的最大值 @property(nonatomic) float maximumValue; //设置滑块左边的图片 @property(nullable, nonatomic,strong) UIImage *minimumValueImage; //设置滑块右边的图片 @property(nullable, nonatomic,strong) UIImage *maximumValueImage; //设置已完成部分轨道颜色 @property(nullable, nonatomic,strong) UIColor *minimumTrackTintColor; //设置未完成部分轨道颜色 @property(nullable, nonatomic,strong) UIColor *maximumTrackTintColor； //设置滑块颜色 @property(nullable, nonatomic,strong) UIColor *thumbTintColor; //设置slider的值 - (void)setValue:(float)value animated:(BOOL)animated; //设置不同状态下滑块的图片 - (void)setThumbImage:(nullable UIImage *)image forState:(UIControlState)state; //设置不同状态下滑动条左侧的图片 - (void)setMinimumTrackImage:(nullable UIImage *)image forState:(UIControlState)state; //设置不同状态下滑动条右侧的图片 - (void)setMaximumTrackImage:(nullable UIImage *)image forState:(UIControlState)state;

下面来看一个完整示例，通过滑动条来调整图片的透明度

#import "ViewController.h"

@interface ViewController ()
@property(nonatomic,strong)UISlider *slider;
@property(nonatomic,strong)UIImageView *imageView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.view addSubview:self.imageView];
    [self.view addSubview:self.slider];
}

//懒加载
- (UISlider *)slider{
    if (_slider == nil) {
        self.slider = [[UISlider alloc]initWithFrame:CGRectMake(20, 60, self.view.frame.size.width - 40, 20)];
        //设置当前slider的值，默认是0
        _slider.value = 0.5;
        //已完成线条颜色
        _slider.minimumTrackTintColor = [UIColor greenColor];
        //未完成部分线条颜色
        _slider.maximumTrackTintColor = [UIColor blackColor];
        //滑块颜色
        _slider.thumbTintColor = [UIColor grayColor];
        //添加事件
        [_slider addTarget:self action:@selector(valueChanged) forControlEvents:UIControlEventValueChanged];
        
    }
    return _slider;
}

//懒加载
- (UIImageView *)imageView{
    if (_imageView == nil) {
        self.imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 100, self.view.frame.size.width, 500)];
        _imageView.contentMode = UIViewContentModeScaleAspectFit;
        _imageView.image = [UIImage imageNamed:@"1"];
        _imageView.layer.masksToBounds = YES;
        _imageView.layer.borderWidth = 1;
        _imageView.alpha = 0.5;
    }
    
    return _imageView;
}

- (void)valueChanged{
    //滑动中随时改变透明度
    [self.imageView setAlpha:self.slider.value];
}


@end

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