ios--解决方案--图片浏览(带缩放+平移)_ios 图片浏览器缩放效果

#import <UIKit/UIKit.h>
@interface ImageViewerController : UIViewController <UIScrollViewDelegate>
@property (strong, nonatomic) IBOutlet UIScrollView *sv;
@property (strong, nonatomic) IBOutlet UIImageView *iv;
@property (strong, nonatomic) IBOutlet UIView *loadingView;
- (void)loadImage:(NSString *)imageURL;
@end

#import "ImageViewerController.h"
@interface ImageViewerController ()
@end
 
@implementation ImageViewerController
@synthesize sv;
 
@synthesize iv;
@synthesize loadingView;
 
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
 
}
 
 
- (void)viewDidLoad
{
    [super viewDidLoad];
 
    // Do any additional setup after loading the view from its nib.
    self.view.backgroundColor = [UIColor blackColor];
 
    [self.view addSubview:loadingView];
    self.sv.delegate = self;
    [self loadImage:@"http://b218.photo.store.qq.com/psb?/V14b2MUB2EAmtl/kbZCrL7A9u.GV4SWP.1EHsReqMEspo1uv5aKcDn*.8c!/b/Yas484HnBAAAYjY684GiBAAA&bo=fAIgA3s!"];
 
}
// 加载图片
- (void)loadImage:(NSString *)imageURL
{
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:imageURL]];
    [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue currentQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error){
 
        if([data length] > 0 && error==nil){
            NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 
            NSRange range = [result rangeOfString:@"404 Not Found"];
            if(range.location != 0){
                [self showLoadFailedAlert];
                [UIView animateWithDuration:0.3 delay:0.3 options:UIViewAnimationCurveLinear animations:^  {
 
                    self.loadingView.alpha = 0;
                } completion:^(BOOL finished){
                    [self.loadingView setHidden:YES];
                }];
                return;
            }
            
            UIImage *image = [UIImage imageWithData:data];
            // 重置UIImageView的Frame，让图片居中显示
 
            CGFloat origin_x = abs(sv.frame.size.width - image.size.width)/2.0;
            CGFloat origin_y = abs(sv.frame.size.height - image.size.height)/2.0;
            self.iv.frame = CGRectMake(origin_x, origin_y, sv.frame.size.width, sv.frame.size.width*image.size.height/image.size.width);
            [self.iv setImage:image];
 
 
            CGSize maxSize = sv.frame.size;
            CGFloat widthRatio = maxSize.width/image.size.width;
            CGFloat heightRatio = maxSize.height/image.size.height;
            CGFloat initialZoom = (widthRatio > heightRatio) ? heightRatio : widthRatio;
            /*
             ** 设置UIScrollView的最大和最小放大级别（注意如果MinimumZoomScale == MaximumZoomScale，
             ** 那么UIScrllView就缩放不了了
             */
            [sv setMinimumZoomScale:initialZoom];
            [sv setMaximumZoomScale:5];
            // 设置UIScrollView初始化缩放级别
 
            [sv setZoomScale:initialZoom];
            
            // 动态隐藏加载界面，从而显示图片
 
            [UIView animateWithDuration:0.3 delay:0.3 options:UIViewAnimationCurveLinear animations:^{
 
                self.loadingView.alpha = 0;
            } completion:^(BOOL finished){
                [self.loadingView setHidden:YES];
            }];
        }else{
            [self showLoadFailedAlert];
 
        }
    }];
}
// 设置UIScrollView中要缩放的视图
 
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return self.iv;
 
}
// 让UIImageView在UIScrollView缩放后居中显示
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    CGFloat offsetX = (scrollView.bounds.size.width > scrollView.contentSize.width)?
    (scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5 : 0.0;
    CGFloat offsetY = (scrollView.bounds.size.height > scrollView.contentSize.height)?
    (scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5 : 0.0;
    iv.center = CGPointMake(scrollView.contentSize.width * 0.5 + offsetX,
                            scrollView.contentSize.height * 0.5 + offsetY);
}
// 显示加载失败的提示对话框
- (void)showLoadFailedAlert
{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示"
                                                   message:@"加载图片失败"
                                                  delegate:nil
                                         cancelButtonTitle:@"确定"
                                         otherButtonTitles:nil];
    [alert show];
}
- (void)viewDidUnload
{
    [super viewDidUnload];
 
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
 
@end