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。
改动头文件内容例如以下：
#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，加入一个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。
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选中这个segue。设置其identifier为ShowFlickrPhoto
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加入一个toolbar和一个imageview到view中，改动toolbarbutton标题为Done，ctrl+drag连接button和FlickrPhotoViewController的done:方法。
再将imageView的outlet也连接上：
打开ViewController.m。加入下面代码到@interface区域中：
@property (nonatomic) BOOL sharing;
改动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，运行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 { // 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;
});
}
}];
}
}
实现done方法。通过点击Donebutton返回到主view：
- (void)done:(id)sender
{
[self.presentingViewController dismissViewControllerAnimated:YES completion:^{}];
}
程序运行效果例如以下：