#import "UIImageView+AFNetworking.h"

找到tableView:cellForRowATindexPath: 方法，并将下面的代码粘贴到最后的return cell; 代码上上面（这里应该有一个注释标记）@H_673_11@ @H_933_944@

 
__weak UITableViewCell *weakCell = cell;
 
[cell.imageView setImageWithURLrequestNSURLrequest alloc] initWithURL:daysWeather.weatherIconURL]
                      placeholderImage[UIImage imagenamed"placeholder.png"]
                               success:rgb(0,UIImage *image{
                                   weakCell.imageView.image = image;
 
                                   //only required if no placeholder is set to force the imageview on the cell to be laid out to house the new image.
                                   //if(weakCell.imageView.frame.size.height==0 || weakCell.imageView.frame.size.width==0 ){
                                   [weakCell setNeedsLayout];
                                   //}
                               }
                               failure*error{
 
                               ];

首先创建一个弱引用(weak)的cell，这样就可以在block中使用这个cell。如果你直接访问cell变量，Xcode会提示一个关于retain循环和内存泄露的警告。@H_673_11@

UIImageView+AFNetworking category定义了一个setImageWithURLrequest… 方法. 这个方法的参数包括：一个指向图片URL的请求，一个占位符图片，一个success block和一个failure block。@H_673_11@

当cell首次被创建的时候，cell中的UIImageView将显示一个占位符图片，直到真正的图片被下载完成。在这里你需要确保占位符的图片与实际图片尺寸大小相同。@H_673_11@

如果尺寸不相同的话，你可以在success block中调用cell的setNeedsLayout方法. 上面代码中对两行代码进行了注释，这是因为这里的占位符图片尺寸正好合适，留着注释，可能在别的程序中需要用到。@H_673_11@

现在生成并运行工程，然后点击之前添加的3个操作中的任意一个，将看到如下内容：@H_673_11@

@H_673_11@ @H_673_127@

@H_673_11@

@H_673_11@

很好! 异步加载图片从来没有这么简单过。@H_673_11@

一个RESTful类

到现在你已经使用类似AFJSONrequestOperation这样的类创建了一次性的http请求。另外，较低级的AFhttpClient类是用来访问单个的web service终端。 对这个AFhttpClient一般是给它设置一个基本的URL，然后用AFhttpClient进行多个请求（而不是像之前的那样，每次请求的时候，都创建一个AFhttpClient）。@H_673_11@

AFhttpClient同样为编码参数、处理multipart表单请求body的构造、管理请求操作和批次入队列操作提供了很强的灵活性，它还处理了整套RESTful (GET,POST,PUT,和 Delete),下面我们就来试试最常用的两个：GET 和 POST.@H_673_11@

: UITableViewController<NSXMLParserDelegate,CLLOCATIOnManagerDelegate,UIActionSheetDelegate>

)httpClientTapped{
    UIActionSheet *actionSheet [UIActionSheet alloc"AFhttpClient" delegate:self cancelButton@R_197_10283@e"Cancel" destructiveButton@R_197_10283@enil otherButton@R_197_10283@es"http POST","http GET",0)">[actionSheet showFromBarButtonItem:sender animated}

)actionSheet(UIActionSheet )actionSheet clickedButtonATindex)buttonIndex// 1
    *baseURL :BaseURLString*parameters "json" forKey"format"// 2
    AFHTTPClient *client [AFHTTPClient alloc] initWithBaseURL:baseURL[client registerHTTPOperationClass[AFJSONRequestOperation class[client setDefaultHeader"Accept" value"application/json"(buttonIndex==[client postPath"weather.php"
              parameters:parameters
                 success(AFHTTPRequestOperation *operation,144)">id responseObject{
                     self.weather = responseObject;
                     self.title "HTTP POST";
                     ];
                 }
                 failure{
                     UIAlertView "Error Retrieving Weather"
                                                                  message]
                                                                 delegatenil
                                                        cancelButtonTitle];
                     ];
 
                 }
         [client getPath"weather.php"
             parameters:parameters
                success{
                    self.weather = responseObject;
                    self.title "HTTP GET";
                    ];
                }
                failure{
                    UIAlertView "Error Retrieving Weather"
                                                                 message]
                                                                delegatenil
                                                       cancelButtonTitle];
                    ];
 
                }

#import "AFhttpClient.h"
 
@protocol WeatherhttpClientDelegate;
 
@interface WeatherhttpClient : AFhttpClient
 
(weak) id<WeatherhttpClientDelegate> delegate;
 
+ (WeatherhttpClient )sharedWeatherhttpClient;
)initWithBaseURL()url;
)updateWeatherAtLocation(CLLocation )location forNumberOfDaysint)number;
 
@end
 
@protocol WeatherHttpClientDelegate <NSObject>
)weatherHTTPClient)client didUpdateWithWeather)weather;
)client didFailWithError()error;
@end

)sharedWeatherhttpClient
*urlStr "http://free.worldweatheronline.com/feed/";
 
    static dispatch_once_t pred;
    static WeatherhttpClient *_sharedWeatherhttpClient nil;
 
    dispatch_once&pred,^{ _sharedWeatherhttpClient [self alloc:urlStr]; );
    return _sharedWeatherhttpClient;
}
 
)url
{
    self [super initWithBaseURL];
    !selfreturn [self registerhttpOperationClass[self setDefaultHeader];
 
    return self;
}

)number{
    [parameters setObject"%d",number"num_of_days""%f,%f",location.coordinate.latitude,location.coordinate.longitude"q""7f3a3480fc162445131401" forKey"key"[self getPath"weather.ashx"
       parameters:parameters
          success[self.delegate respondsToSelector@selector(weatherHTTPClient:didUpdateWithWeather)
                [self.delegate weatherHTTPClient:self didUpdateWithWeather:responseObject:didFailWithError:self didFailWithError:error}

#import "WeatherhttpClient.h"
 
: UITableViewController <NSXMLParserDelegate,UIActionSheetDelegate,WeatherhttpClientDelegate>

) CLLOCATIOnManager *@H_128_9@manager;

    self.manager [CLLOCATIOnManager alloc] init];
    self.manager.delegate = self;

)LOCATIOnManager(CLLOCATIOnManager )@H_128_9@manager didupdateToLOCATIOn)newLOCATIOn fromLOCATIOn)oldLOCATIOn//if the LOCATIOn is more than 5 minutes old ignore
    [newLOCATIOn.timestamp timeIntervalSinceNow]< 300[self.manager stopupdatingLOCATIOn];
 
        WeatherhttpClient [WeatherhttpClient sharedWeatherhttpClient];
        client.delegate = self;
        [client updateWeatherAtLOCATIOn:newLOCATIOn fornumberOfDays:5];  
    }

)aWeather= aWeather;
    self.@R_197_10283@e "API updated";
    )error{
    UIAlertView "Error Retrieving Weather"
                                                 message]
                                                delegatenil
                                       cancelButton@R_197_10283@e}

)apiTapped{
    [self.manager startupdatingLOCATIOn}

BOOL)application(UIApplication )application didFinishLaunchingWithOptions)launchOptions
[AFNetworkActivityInDicatoRMANager sharedManager].enabled YES;
    YES;
}

)updateBACkgroundImage//Store this image on the same server as the weather cAnned files
    "http://www.scott-sherwood.com/wp-content/uploads/2013/01/scene.png"];
    AFImageRequestOperation [AFImageRequestOperation imageRequestOperationWithRequest:request
        imageProcessingBlocknil
        success{
            self.backgroundImageView.image = image;
            [self saveImage:image withFilename"background.png"{
            NSLog("Error %@",0)">);
    }

)deleteBACkgroundImage*path;
	*paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,0)">);
	path [paths objectAtIndex] stringByAppendingPathComponent"WeatherHTTPClientImages/"];
 
    *error;
    [NSFileManager defaultManager] removeItemAtPath:path error:&error];
 
    *desc [self.weatherDictionary weatherDescription[self start:desc}