#import "ViewController.h"

@interface ViewController ()<UIScrollViewDelegate>
{
    UIImageView *imageView;
}

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    
    UIScrollView *scrollView = [[UIScrollView alloc]initWithFrame:self.view.bounds];
    
    scrollView.contentSize = self.view.bounds.size;
    
    [self.view addSubview:scrollView];
    
    
    imageView = [[UIImageView alloc]initWithFrame:self.view.bounds];
    
    imageView.image = [UIImage imageNamed:@"scene1.jpg"];
    
    imageView.contentMode = UIViewContentModeScaleAspectFit;
    
    //开启触摸响应
    imageView.userInteractionEnabled = YES;
    
    //开启多点触摸
    imageView.multipleTouchEnabled = YES;
    
    [scrollView addSubview:imageView];
    
    /*_______________________________________________________________*/
    
    //1⃣️设置缩放范围
    
    //最大倍数
    scrollView.maximumZoomScale = 2.0;
    //最小倍数
    scrollView.minimumZoomScale = 0.5;
    
    //反弹效果
    //    scrollView.bouncesZoom = NO;
    
    //2⃣️设置代理对象
    scrollView.delegate = self;
    
    
    
    
}

//3⃣️
//返回一个将要缩放的视图
- (nullable UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
    return imageView;
}

//缩放时调用
- (void)scrollViewDidZoom:(UIScrollView *)scrollView{
    
    NSLog(@"%f",scrollView.zoomScale);
    
}

//将要开始缩放时
- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(nullable UIView *)view{
    
}
//已经结束缩放时
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(nullable UIView *)view atScale:(CGFloat)scale{
    
}

@end

option + 左键 缩放

屏幕快照 2016-03-04 下午7.07.07.png