AFNetWorking

AFNetwork是一個輕量級的網絡請求api類庫。是以NSURLConnection, NSOperation和其他方法爲基礎的。

下面這個例子是用來處理json請求的：
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.下載AFNetwork，點擊下載
2.將文件夾名稱爲AFNetworking拖入到你的工程項目即可

常見問題：
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和它的子類繼承NSOperation的，允許請求被取消，暫停/恢復和由NSOperationQueue進行管理。
＊AFURLConnectionOperation也可以讓你輕鬆得完成上傳和下載，處理驗證，監控上傳和下載進度，控制的緩存。
＊AFHTTPRequestOperation和它得子類可以基於http狀態和內容列下來區分是否成功請求了
＊AFNetworking可以將遠程媒體數據類型（NSData）轉化爲可用的格式，比如如JSON，XML，圖像和plist。
＊AFHTTPClient提供了一個方便的網絡交互接口，包括默認頭，身份驗證，是否連接到網絡，批量處理操作，查詢字符串參數序列化，已經多種表單請求
＊的UIImageView+ AFNetworking增加了一個方便的方法來異步加載圖像。

2. AFNetworking是否支持緩存？
可以，NSURLCache及其子類提供了很多高級接口用於處理緩存
如果你想將緩存存儲再磁盤，推薦使用SDURLCache

3.如何使用AFNetworking上傳一個文件？
NSData *p_w_picpathData = UIImagePNGRepresentation(p_w_picpath);
NSURLRequest *request = [client multipartFormRequestWithMethod:@"POST" path:@"/upload" parameters:nil constructingBodyWithBlock: ^(id <AFMultipartFormData> formData) {
[formData appendPartWithFileData:p_w_picpathData mimeType:@"p_w_picpath/png" name:@"avatar"];
}];


4.如何使用AFNetworking下載一個文件？
先創建一個AFURLConnectionOperation對象，然後再使用它的屬性outputStream進行處理
operation.outputStream = [NSOutputStream outputStreamToFileAtPath:@"download.zip" append:NO];

5.如何解決：SystemConfiguration framework not found in project
請導入：
#import <SystemConfiguration/SystemConfiguration.h>
#import <MobileCoreServices/MobileCoreServices.h>

6.當應用程序退出時，如何保持持續的請求？
AFURLConnectionOperation有一個叫setShouldExecuteAsBackgroundTaskWithExpirationHandler:的方法用於處理在應用程序進入後臺後，進行持續的請求
[self setShouldExecuteAsBackgroundTaskWithExpirationHandler:^{
}];



一些實例：
1.XML 請求
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.圖片請求：
UIImageView *p_w_picpathView = [[UIImageView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 100.0f, 100.0f)];
[p_w_picpathView setImageWithURL:[NSURL URLWithString:@"http://i.imgur.com/r4uwx.jpg"] placeholderImage:[UIImage p_w_picpathNamed:@"placeholder-avatar"]];

3.圖片上傳處理，監測上傳狀態：
didiwei 17:28:57
NSURL *url = [NSURL URLWithString:@"http://api-base-url.com"];
AFHTTPClient *httpClient = [[AFHTTPClient alloc] initWithBaseURL:url];
NSData *p_w_picpathData = UIImageJPEGRepresentation([UIImage p_w_picpathNamed:@"avatar.jpg"], 0.5);
NSMutableURLRequest *request = [httpClient multipartFormRequestWithMethod:@"POST" path:@"/upload" parameters:nil constructingBodyWithBlock: ^(id <AFMultipartFormData>formData) {
[formData appendPartWithFileData:p_w_picpathData name:@"avatar" fileName:@"avatar.jpg" mimeType:@"p_w_picpath/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.在線流媒體請求
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://localhost:8080/encode"]];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
operation.inputStream = [NSInputStream inputStreamWithFileAtPath:[[NSBundle mainBundle] pathForResource:@"large-p_w_picpath" ofType:@"tiff"]];
operation.outputStream = [NSOutputStream outputStreamToMemory];
[operation start];