UISlider显示进度(并且实现图片缩放)

图片展示效果如下：

其他没什么好说的，直接上代码：

RootView.h:

 #import <UIKit/UIKit.h>
 
 @interface RootView : UIView
 @property (nonatomic, strong) UISlider *slider;
 @property (nonatomic, strong) UILabel *label;
 @property (nonatomic, strong) UIImageView *imageView;
 
 @end

RootView.m:

 #import "RootView.h"
 
 @implementation RootView
 
 - (instancetype)initWithFrame:(CGRect)frame {
     if (self = [super initWithFrame:frame]) {
         // 添加子视图
         [self add];
     }
     return self;
 }
 
 // 添加子视图
 - (void)add {
 
     // 添加slider
     self.slider = [[UISlider alloc] initWithFrame:CGRectMake(, , self.frame.size.width -  * , )];
     self.slider.minimumValue = 0.0;
     self.slider.maximumValue = 100.0;
     [self addSubview:self.slider];
 
     // 添加label
     self.label = [[UILabel alloc] init];
     self.label.textAlignment = NSTextAlignmentCenter;
     self.label.layer.cornerRadius = ;
     self.label.layer.borderWidth = ;
     self.label.layer.borderColor = [UIColor greenColor].CGColor;
     self.label.font = [UIFont fontWithName:@"Gill Sans" size:];
     [self addSubview:self.label];
 
     // 添加图片
     self.imageView = [[UIImageView alloc] initWithFrame:CGRectMake(, , , )];
     self.imageView.image = [UIImage imageNamed:@"u=347478478,461363313&fm=11&gp=0.jpg"];
     [self addSubview:self.imageView];
 
 }
 
 @end

RootViewController.m:

 #import "RootViewController.h"
 #import "RootView.h"
 
 @interface RootViewController ()
 @property (nonatomic, strong) RootView *rootView;
 
 @end
 
 @implementation RootViewController
 
 - (void)loadView {
     self.rootView = [[RootView alloc] initWithFrame:[UIScreen mainScreen].bounds];
     self.view = self.rootView;
 }
 
 - (void)viewDidLoad {
     [super viewDidLoad];
 
     // 为slider添加一个滑动事件(注意添加的事件是改变数据的事件UIControlEventValueChanged)
     [self.rootView.slider addTarget:self action:@selector(slding:) forControlEvents:UIControlEventValueChanged];
 }
 
 #pragma mark - 实现滑动事件
 - (void)slding:(UISlider *)sender {
 
     // 1.实现滑动显示进度（百分比）
     // 创建一个图片控制器，并且获取slider控件的某一个子控件（就是进度条的滑块,位置是2）
     UIImageView *imageView = [self.rootView.slider.subviews objectAtIndex:];
     // 获取滑块在父视图上的位置
     CGRect nowRect = [self.rootView convertRect:imageView.frame fromView:imageView.superview];
     // 根据滑块的位置来设置label的位置
     self.rootView.label.frame = CGRectMake(nowRect.origin.x - , nowRect.origin.y - , nowRect.size.width, nowRect.size.height);
     // 定义一个NSInteger类型的变量来接收滑块当前滑动到的位置
     NSInteger x = self.rootView.slider.value;
     // 在label上显示滑块的位置
     self.rootView.label.text = [NSString stringWithFormat:@"%ld%%",x];
 
     // 2.实现图片缩放
     // 创建一个图片控制器，并且获取slider控件的某一个子控件（就是进度条的滑块,位置是2）
     UIImageView *imageView1 = [self.rootView.slider.subviews objectAtIndex:];
     // 获取滑块在父视图上的位置
     CGRect imageRect = [self.rootView convertRect:imageView1.frame fromView:imageView.superview];
     // 重新设置图片的frame
     self.rootView.imageView.frame = CGRectMake( - (imageRect.origin.x - ) / ,  - (imageRect.origin.x - ) / 2,  + imageRect.origin.x - ,  + imageRect.origin.x - );
 }
 
 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
     // Dispose of any resources that can be recreated.
 }
 
 @end