这一节，我们实现通过点击图片将图片放大显示的功能。
首先我们创建一个名为FlickrPhotoViewConroller的类，这个类继承于UIViewController。修改头文件内容如下：
#import <UIKit/UIKit.h>@class FlickrPhoto;@interface FlickrPhotoViewConroller : UIViewController@property (nonatomic, strong) FlickrPhoto *flickrPhoto;@end声明outlet和action：
#import "FlickrPhotoViewConroller.h"#import "Flickr.h"#import "FlickrPhoto.h"@interface FlickrPhotoViewConroller ()@property (weak) IBOutlet UIImageView *imageView;- (IBAction)done:(id)sender;@end打开storyboard，添加一个UIViewController到storyboard中，设置这个view的class为FlickrPhotoViewConroller。
从主view使用ctrl+drag创建一个到Flickr Photo view controller的modal segue。
选中这个segue，设置其identifier为ShowFlickrPhoto
添加一个toolbar和一个imageview到view中，修改toolbar按钮标题为Done，ctrl+drag连接按钮和FlickrPhotoViewController的done:方法。
再将imageView的outlet也连接上：
打开ViewController.m，，添加以下代码到@interface区域中：
@property (nonatomic) BOOL sharing;修改didSelectItemAtIndexPath方法：
if (!self.sharing){NSString *searchTerm = self.searchs[indexPath.section];FlickrPhoto *photo = self.searchResults[searchTerm][indexPath.row];[self performSegueWithIdentifier:@"ShowFlickrPhoto" sender:photo];[self.collectionView deselectItemAtIndexPath:indexPath animated:YES];}else{}当用户点击某幅缩略图时，执行ShowFlickrPhoto segue。#import "FlickrPhotoViewConroller.h"- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{if ([segue.identifier isEqualToString:@"ShowFlickrPhoto"]){FlickrPhotoViewConroller *flickrPhotoViewController = segue.destinationViewController;flickrPhotoViewController.flickrPhoto = sender;}}实现viewWillAppear方法，显示大图片到view中：
-(void)viewDidAppear:(BOOL)animated { // 1if(self.flickrPhoto.largeImage){self.imageView.image = self.flickrPhoto.largeImage;}else{ // 2self.imageView.image = self.flickrPhoto.thumbnail;// 3[Flickr loadImageForPhoto:self.flickrPhoto thumbnail:NO completionBlock:^(UIImage *photoImage, NSError *error) {if(!error) { // 4dispatch_async(dispatch_get_main_queue(), ^{ self.imageView.image =self.flickrPhoto.largeImage;});}}];}}实现done方法，通过点击Done按钮返回到主view：
– (void)done:(id)sender{[self.presentingViewController dismissViewControllerAnimated:YES completion:^{}];}程序执行效果如下：
却只能这样。只有对爱的人，我们才会斤斤计较，锱铢必较。
