AFNetworking 学习笔记

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。
Github:https://github.com/AFNetworking/AFNetworking/

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
   ＊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  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 
#import 

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：

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 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];