基本使用步骤

1. 创建一个scrollView，进行frame等常规设置，并将其添加到控制器view
   UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
   scrollView.backgroundColor = [UIColor grayColor];
   [self.view addSubview:scrollView];`

2. 将需要展示的内容addSubView到scrollView中
   UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"cao"]]; imageView.frame = CGRectMake(0, 0, imageView.image.size.width, imageView.image.size.height); [scrollView addSubview:imageView];

3. 设置scrollView的contentSize，一般比frame范围大，使scrollView可以滚动
   scrollView.contentSize = CGSizeMake(imageView.frame.size.width, imageView.frame.size.height);

4. 你还可以设置scrollView的其他属性
   scrollView.showsHorizontalScrollIndicator = NO; scrollView.showsVerticalScrollIndicator = NO; scrollView.contentInset = UIEdgeInsetsMake(50, 50, 50, 50); NSLog(@"%f",scrollView.contentOffset.x);

缩放手势的步骤

1. 设置控制器为scrollView的代理
   @interface ViewController () <UIScrollViewDelegate> scrollView.delegate = self;
2. 设置缩放的范围（最大比例和最小比例）
   scrollView.maximumZoomScale = 2.0; scrollView.minimumZoomScale = 0.5;
3. 实现scrollView的代理方法，来确定scrollView内需要缩放的控件
   -(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView { return self.imageView; }