iOS使用UIScorllView实现两指缩放功能

#import "ViewController.h"
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
@property (strong, nonatomic) UIImageView *imageView;
@end
@implementation ViewController
- (void)viewDidLoad {
  [super viewDidLoad];
  _scrollView.minimumZoomScale = 1.0;   // 最小缩放值
  _scrollView.maximumZoomScale = 10.0;  // 最大缩放值
  [_scrollView setZoomScale:_scrollView.minimumZoomScale];  // 初始时候的缩放值
  _scrollView.delegate = self;
  _imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image"]];
  _imageView.frame = self.view.frame;
  [_scrollView addSubview:_imageView];
}
#pragma mark - 返回需要缩放的控件
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
  return _imageView;
}
- (void)didReceiveMemoryWarning {
  [super didReceiveMemoryWarning];
}
@end