使用scrollview实现图片放大缩小

 1 #import "ViewController.h"
 2 #import <UIKit/UIMenuController.h>
 3 
 4 @interface ViewController ()<UIScrollViewDelegate>
 5 @property (strong, nonatomic) UIScrollView *scrView;
 6 
 7 @property (nonatomic,strong)UIImageView *imgv;
 8 @end
 9 
10 @implementation ViewController
11 
12 - (void)viewDidLoad {
13     [super viewDidLoad];
14     //[[UILabel appearance] setTextColor:[UIColor yellowColor]];
15     self.scrView = [[UIScrollView alloc]initWithFrame:self.view.bounds];
16     self.scrView.contentSize = CGSizeMake(800, 1800);
17     self.scrView.backgroundColor =  [UIColor yellowColor];
18     [self.view addSubview:self.scrView];
19 
20 
21     // 设置放大缩小的比例
22     self.scrView.multipleTouchEnabled = YES;//打开多指触控
23     self.scrView.maximumZoomScale = 2.0;
24     self.scrView.minimumZoomScale = 0.5;
25     self.scrView.zoomScale = 3.0;
26 
27     self.scrView.delegate = self;
28 
29     UIImageView *imgv = [[UIImageView alloc]initWithFrame:CGRectMake(150, 150, 150, 150)];
30     imgv.backgroundColor = [UIColor grayColor];
31     [self.scrView addSubview:imgv];
32     self.imgv = imgv;
33 
34 }
35 
36 // *** 必须实现的代理方法
37 
38 -(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
39     return self.imgv;
40 }
41 // ***是图片保持位于视图中心
42 
43 -(void)scrollViewDidZoom:(UIScrollView *)scrollView{
44     self.imgv.center = self.view.center;
45 }