#import "RootViewController.h"

 @interface RootViewController ()<UIScrollViewDelegate>

 {

     UIImageView *imageView;

     UILabel *scaleRatioLabel;// 显示倍率用的Label

 }

 @property (nonatomic, strong)UIScrollView *scrollView;

 @end

 @implementation RootViewController

 - (void)dealloc

 {

     self.scrollView = nil;

 }

 - (void)viewDidLoad {

     [super viewDidLoad];

     self.scrollView = [[UIScrollView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

     self.scrollView.delegate = self;

     [self.view addSubview:self.scrollView];

     imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"1-3.jpg"]];

     [imageView setCenter:CGPointMake([UIScreen mainScreen].bounds.size.width/2.0, [UIScreen mainScreen].bounds.size.height/2.0)];

     [self.scrollView addSubview:imageView];

     //内容大小与图片大小一致

     self.scrollView.contentSize = imageView.frame.size;

     // 最小缩放比例

     self.scrollView.minimumZoomScale = 0.2f;

     // 最大缩放比例

     self.scrollView.maximumZoomScale = 5.0f;

     // 用来显示倍率的Label

     scaleRatioLabel = [[UILabel alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2.0 - , [UIScreen mainScreen].bounds.size.height/2.0 - 12.5, , )];

     [scaleRatioLabel setBackgroundColor:[UIColor clearColor]];

     [self.view addSubview:scaleRatioLabel];

 }

 #pragma mark - UIScrollViewDelegate

 // 设置要缩放的控件

 - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView

 {

     return imageView;

 }

 // 处理结束缩放事件

 - (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale

 {

     [self.view bringSubviewToFront:scaleRatioLabel];

     [scaleRatioLabel setAlpha:0.6f];

     [scaleRatioLabel setBackgroundColor:[UIColor lightGrayColor]];

     scaleRatioLabel.text = [NSString stringWithFormat:@" x%.1f",scale];

     [UIView transitionWithView:scaleRatioLabel duration:2.0f options:UIViewAnimationOptionCurveEaseInOut animations:^{

         scaleRatioLabel.alpha = 0.0f;

     } completion:nil];

 }

 @end