這一節，我們實現通過點擊圖片將圖片放大顯示的功能。

首先我們創建一個名為FlickrPhotoViewConroller的類，這個類繼承於UIViewController。修改頭文件內容如下：

 

#import 
@class FlickrPhoto;

@interface FlickrPhotoViewConroller : UIViewController
@property (nonatomic, strong) FlickrPhoto *flickrPhoto;
@end

聲明outlet和action：

 

 

#import "FlickrPhotoViewConroller.h"
#import "Flickr.h"
#import "FlickrPhoto.h"

@interface FlickrPhotoViewConroller ()

@property (weak) IBOutlet UIImageView *imageView;
- (IBAction)done:(id)sender;

@end

打開storyboard，添加一個UIViewController到storyboard中，設置這個view的class為FlickrPhotoViewConroller。

 

從主view使用ctrl+drag創建一個到Flickr Photo view controller的modal segue。

選中這個segue，設置其identifier為ShowFlickrPhoto

 

添加一個toolbar和一個imageview到view中，修改toolbar按鈕標題為Done，ctrl+drag連接按鈕和FlickrPhotoViewController的done:方法。

再將imageView的outlet也連接上：

打開ViewController.m，添加以下代碼到@interface區域中：

 

@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
    {
        
    }

當用戶點擊某幅縮略圖時，執行ShowFlickrPhoto segue。

#import "FlickrPhotoViewConroller.h"
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"ShowFlickrPhoto"])
    {
        FlickrPhotoViewConroller *flickrPhotoViewController = segue.destinationViewController;
        flickrPhotoViewController.flickrPhoto = sender;
    }
}

實現viewWillAppear方法，顯示大圖片到view中：

 

 

-(void)viewDidAppear:(BOOL)animated { // 1
    if(self.flickrPhoto.largeImage)
    {
        self.imageView.image = self.flickrPhoto.largeImage;
    }
    else
    { // 2
        self.imageView.image = self.flickrPhoto.thumbnail;
        // 3
        [Flickr loadImageForPhoto:self.flickrPhoto thumbnail:NO completionBlock:^(UIImage *photoImage, NSError *error) {
            if(!error) { // 4
                dispatch_async(dispatch_get_main_queue(), ^{ self.imageView.image =
                    self.flickrPhoto.largeImage;
                });
            }
        }];
    }
}

實現done方法，通過點擊Done按鈕返回到主view：

 

 

- (void)done:(id)sender
{
    [self.presentingViewController dismissViewControllerAnimated:YES completion:^{}];
}

程序執行效果如下：