下面这个例子是用来处理json请求的：NSURL *url = [NSURL URLWithString:@"https://alpha-api.app.net/stream/0/posts/stream/global"];NSURLRequest *request = [NSURLRequest requestWithURL:url];AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {    NSLog(@"App.net Global Stream: %@", JSON);} failure:nil];[operation start];

常见问题：1. AFNetworking作用都有哪些？NSURLConnection提供了+sendAsynchronousRequest:queue:completionHandler:和+sendAsynchronousRequest:queue:completionHandler: ，但是AFNetworking提供了更好的功能＊AFURLConnectionOperation和它的子类继承NSOperation的，允许请求被取消，暂停/恢复和由NSOperationQueue进行管理。＊AFURLConnectionOperation也可以让你轻松得完成上传和下载，处理验证，监控上传和下载进度，控制的缓存。＊AFHTTPRequestOperation和它得子类可以基于http状态和内容列下来区分是否成功请求了＊AFNetworking可以将远程媒体数据类型（NSData）转化为可用的格式，比如如JSON，XML，图像和plist。＊AFHTTPClient提供了一个方便的网络交互接口，包括默认头，身份验证，是否连接到网络，批量处理操作，查询字符串参数序列化，已经多种表单请求＊的UIImageView+ AFNetworking增加了一个方便的方法来异步加载图像。2. AFNetworking是否支持缓存？可以，NSURLCache及其子类提供了很多高级接口用于处理缓存如果你想将缓存存储再磁盘，推荐使用SDURLCache

3.如何使用AFNetworking上传一个文件？
NSData *imageData = http://www.mamicode.com/UIImagePNGRepresentation(image);
NSURLRequest *request = [client multipartFormRequestWithMethod:@"POST" path:@"/upload" parameters:nil constructingBodyWithBlock: ^(id <AFMultipartFormData> formData) {
  [formData appendPartWithFileData:imageData mimeType:@"image/png" name:@"avatar"];
}];


4.如何使用AFNetworking下载一个文件？
先创建一个AFURLConnectionOperation对象，然后再使用它的属性outputStream进行处理
operation.outputStream = [NSOutputStream outputStreamToFileAtPath:@"download.zip" append:NO];

5.如何解决：SystemConfiguration framework not found in project
请导入：
#import <SystemConfiguration/SystemConfiguration.h>
#import <MobileCoreServices/MobileCoreServices.h>

6.当应用程序退出时，如何保持持续的请求？
AFURLConnectionOperation有一个叫setShouldExecuteAsBackgroundTaskWithExpirationHandler:的方法用于处理在应用程序进入后台后，进行持续的请求
[self setShouldExecuteAsBackgroundTaskWithExpirationHandler:^{
}];

一些实例：
1.XML 请求NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://api.flickr.com/services/rest/?method=flickr.groups.browse&api_key=b6300e17ad3c506e706cb0072175d047&cat_id=34427469792%40N01&format=rest"]];AFXMLRequestOperation *operation = [AFXMLRequestOperation XMLParserRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, NSXMLParser *XMLParser) {  XMLParser.delegate = self;  [XMLParser parse];} failure:nil];[operation start];2.图片请求：UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 100.0f, 100.0f)];[imageView setImageWithURL:[NSURL URLWithString:@"http://i.imgur.com/r4uwx.jpg"] placeholderImage:[UIImage imageNamed:@"placeholder-avatar"]];3.图片上传处理，监测上传状态：didiwei  17:28:57NSURL *url = [NSURL URLWithString:@"http://api-base-url.com"];AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:url];NSData *imageData = http://www.mamicode.com/UIImageJPEGRepresentation([UIImage imageNamed:@"avatar.jpg"], 0.5);NSMutableURLRequest *request = [httpClient multipartFormRequestWithMethod:@"POST" path:@"/upload" parameters:nil constructingBodyWithBlock: ^(id <AFMultipartFormData>formData) {    [formData appendPartWithFileData:imageData name:@"avatar" fileName:@"avatar.jpg" mimeType:@"image/jpeg"];}];AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];[operation setUploadProgressBlock:^(NSUInteger bytesWritten, long long totalBytesWritten, long long totalBytesExpectedToWrite) {    NSLog(@"Sent %lld of %lld bytes", totalBytesWritten, totalBytesExpectedToWrite);}];[operation start];4.在线流媒体请求NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://localhost:8080/encode"]];AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];operation.inputStream = [NSInputStream inputStreamWithFileAtPath:[[NSBundle mainBundle] pathForResource:@"large-image" ofType:@"tiff"]];operation.outputStream = [NSOutputStream outputStreamToMemory];[operation start];