准备
首先，你需要将AFNetworking 框架包含到工程中。如果你还没有AFNetworking的话，在这里下载最新的版本：
https://github.com/AFNetworking/AFNetworking
当你解压出下载的文件后，你将看到其中有一个AFNetworking子文件夹，里面全是.h 和 .m 文件, 如下高亮显示的:

将AFNetworking拖拽到Xcode工程中.

当出现了添加文件的选项时，确保勾选上Copy items into destination group's folder (if needed) 和 Create groups for any added folders.
将AFNetworking添加到预编译头文件，意味着这个框架会被自动的添加到工程的所有源代码文件中。

常用方法介绍
方法一：GET 请求
代码如下：

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:@"http://example.com/resources.json" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseobject) {
    NSLog(@"JSON: %@", responseobject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

方法二：POST 请求
代码如下：

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
NSDictionary *parameters = @{@"foo": @"bar"};
[manager POST:@"http://example.com/resources.json" parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseobject) {
    NSLog(@"JSON: %@", responseobject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

方法三：POST Multi-Part Request
代码如下：

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
NSDictionary *parameters = @{@"foo": @"bar"};
NSURL *filePath = [NSURL fileURLWithPath:@"file://path/to/image.png"];
[manager POST:@"http://example.com/resources.json" parameters:parameters constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
    [formData appendPartWithFileURL:filePath name:@"image" error:nil];
} success:^(AFHTTPRequestOperation *operation, id responseobject) {
    NSLog(@"Success: %@", responseobject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

方法四：创建一个下载文件任务
代码如下：

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

NSURL *URL = [NSURL URLWithString:@"http://example.com/download.zip"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];

NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:nil destination:^NSURL *(NSURL *targetPath, NSURLResponse *response) {
    NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
    return [documentsDirectoryURL URLByAppendingPathComponent:[response suggestedFilename]];
} completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {
    NSLog(@"File downloaded to: %@", filePath);
}];
[downloadTask resume];

方法五：创建一个上传文件任务
代码如下：

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

NSURL *URL = [NSURL URLWithString:@"http://example.com/upload"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];

NSURL *filePath = [NSURL fileURLWithPath:@"file://path/to/image.png"];
NSURLSessionUploadTask *uploadTask = [manager uploadTaskWithRequest:request fromFile:filePath progress:nil completionHandler:^(NSURLResponse *response, id responseobject, NSError *error) {
    if (error) {
        NSLog(@"Error: %@", error);
    } else {
        NSLog(@"Success: %@ %@", response, responseobject);
    }
}];
[uploadTask resume];

方法六：创建一个上传文件任务并显示进度
代码如下：

NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:@"http://example.com/upload" parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
        [formData appendPartWithFileURL:[NSURL fileURLWithPath:@"file://path/to/image.jpg"] name:@"file" fileName:@"filename.jpg" mimeType:@"image/jpeg" error:nil];
    } error:nil];

AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
NSProgress *progress = nil;

NSURLSessionUploadTask *uploadTask = [manager uploadTaskWithStreamedRequest:request progress:&progress completionHandler:^(NSURLResponse *response, id responseobject, NSError *error) {
    if (error) {
        NSLog(@"Error: %@", error);
    } else {
        NSLog(@"%@ %@", response, responseobject);
    }
}];
[uploadTask resume];

方法七：创建一个上传数据data任务
代码如下：

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

NSURL *URL = [NSURL URLWithString:@"http://example.com/upload"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];

NSURLSessionDataTask *dataTask = [manager dataTaskWithRequest:request completionHandler:^(NSURLResponse *response, id responseobject, NSError *error) {
    if (error) {
        NSLog(@"Error: %@", error);
    } else {
        NSLog(@"%@ %@", response, responseobject);
    }
}];
[dataTask resume];

方法八：获取网络状态
代码如下：

[[AFNetworkReachabilityManager sharedManager] setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
    NSLog(@"Reachability: %@", AFStringFromNetworkReachabilityStatus(status));
}];

方法九： HTTP Manager Reachability
代码如下：

NSURL *baseURL = [NSURL URLWithString:@"http://example.com/"];
AFHTTPRequestOperationManager *manager = [[AFHTTPRequestOperationManager alloc] initWithBaseURL:baseURL];

NSOperationQueue *operationQueue = manager.operationQueue;
[manager.reachabilityManager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
    switch (status) {
        case AFNetworkReachabilityStatusReachableViaWWAN:
        case AFNetworkReachabilityStatusReachableViaWiFi:
            [operationQueue setSuspended:NO];
            break;
        case AFNetworkReachabilityStatusNotReachable:
        default:
            [operationQueue setSuspended:YES];
            break;
    }
}];

[manager.reachabilityManager startMonitoring];

方法十：AFHTTPRequestOperation的GET请求
代码如下：

NSURL *URL = [NSURL URLWithString:@"http://example.com/resources/123.json"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];
AFHTTPRequestOperation *op = [[AFHTTPRequestOperation alloc] initWithRequest:request];
op.responseSerializer = [AFJSONResponseSerializer serializer];
[op setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseobject) {
    NSLog(@"JSON: %@", responseobject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];
[[NSOperationQueue mainQueue] addOperation:op]; 

方法十一：Batch of Operations
代码如下：

NSMutableArray *mutableOperations = [NSMutableArray array];
for (NSURL *fileURL in filesToUpload) {
    NSURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:@"http://example.com/upload" parameters:nil constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
        [formData appendPartWithFileURL:fileURL name:@"images[]" error:nil];
    }];

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

    [mutableOperations addObject:operation];
}

NSArray *operations = [AFURLConnectionOperation batchOfRequestOperations:@[...] progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
    NSLog(@"%lu of %lu complete", numberOfFinishedOperations, totalNumberOfOperations);
} completionBlock:^(NSArray *operations) {
    NSLog(@"All operations in batch complete");
}];
[[NSOperationQueue mainQueue] addOperations:operations waitUntilFinished:NO];

方法十二：获取请求的一些信息(我也没有用过，不太常用)
代码如下：

Request Serialization

Request serializers create requests from URL strings, encoding parameters as either a query string or HTTP body.

NSString *URLString = @"http://example.com";
NSDictionary *parameters = @{@"foo": @"bar", @"baz": @[@1, @2, @3]};
Query String Parameter Encoding

[[AFHTTPRequestSerializer serializer] requestWithMethod:@"GET" URLString:URLString parameters:parameters error:nil];

GET http://example.com?foo=bar&baz[]=1&baz[]=2&baz[]=3
URL Form Parameter Encoding

[[AFHTTPRequestSerializer serializer] requestWithMethod:@"POST" URLString:URLString parameters:parameters];

POST http://example.com/
Content-Type: application/x-www-form-urlencoded

foo=bar&baz[]=1&baz[]=2&baz[]=3
JSON Parameter Encoding

[[AFJSONRequestSerializer serializer] requestWithMethod:@"POST" URLString:URLString parameters:parameters];

POST http://example.com/
Content-Type: application/json

{"foo": "bar", "baz": [1,2,3]}