AFNetWorking使用

AFNetwork是一个轻量级的网络请求api类库。是以NSURLConnection, NSOperation和其他方法为基础的。

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]; 
使用方法： 
1.下载AFNetwork， 点击下载 
2.将文件夹名称为AFNetworking拖入到你的工程项目即可 
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 = 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  17:28:57 
NSURL *url = [NSURL URLWithString:@"http://api-base-url.com"]; 
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:url]; 
NSData *imageData = 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];