AFNetworking 3.0 源码解读（六）之 AFHTTPSessionManager

AFHTTPSessionManager相对来说比较好理解，代码也比较短。但却是我们平时可能使用最多的类。

前言

AFHTTPSessionManager是AFURLSessionManager的子类，是专门为HTTP请求设计的。里边涉及到了GET,POST,PUT,DELETE 等等HTTPMehtod。因此我们要想正确的使用各种方法，就要理解每个method的含义。

可以通过这篇文章来了解HTTP Method详细解读(GET HEAD POST OPTIONS PUT DELETE TRACE CONNECT)

1.相对路径(relative)

假如有一个基础路径NSURL *baseURL = [NSURL URLWithString:@"http://example.com/v1/"];我们暂时命名为baseURL.所谓相对肯定跟这个baseURL有关系。

我们可以通过NSURL +URLWithString:relativeToURL:这个方法来获取一个路径，至于怎么使用，我们通过一个例子来说明：

NSURL *baseURL = [NSURL URLWithString:@"http://example.com/v1/"];

[NSURL URLWithString:@"foo" relativeToURL:baseURL];                  // http://example.com/v1/foo

[NSURL URLWithString:@"foo?bar=baz" relativeToURL:baseURL];          // http://example.com/v1/foo?bar=baz

[NSURL URLWithString:@"/foo" relativeToURL:baseURL];                 // http://example.com/foo

[NSURL URLWithString:@"foo/" relativeToURL:baseURL];                 // http://example.com/v1/foo

[NSURL URLWithString:@"/foo/" relativeToURL:baseURL];                // http://example.com/foo/

[NSURL URLWithString:@"http://example2.com/" relativeToURL:baseURL]; // http://example2.com/

至于 绝对路径 和 相对路径 的定义，使用方法，优缺点，这里就不提了，大家可以自行了解。说一下为什么使用相对路径吧。

在真实开发中，一般都会有一个线上的服务器和一下测试服务器，当然也可能多个。在ios开发中切换开发环境有好几种方法，

通过target
自定义一个字段HTTPURL，用它来控制路径
通过相对路径来切换接口

2.GET

// 使用GET 方法获取数据，不带进度

- (NSURLSessionDataTask *)GET:(NSString *)URLString

                   parameters:(id)parameters

                      success:(void (^)(NSURLSessionDataTask *task, id responseObject))success

                      failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure

{

    return [self GET:URLString parameters:parameters progress:nil success:success failure:failure];

}

// 使用GET 方法获取数据，带进度

- (NSURLSessionDataTask *)GET:(NSString *)URLString

                   parameters:(id)parameters

                     progress:(void (^)(NSProgress * _Nonnull))downloadProgress

                      success:(void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success

                      failure:(void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure

{

    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"GET"

                                                        URLString:URLString

                                                       parameters:parameters

                                                   uploadProgress:nil

                                                 downloadProgress:downloadProgress

                                                          success:success

                                                          failure:failure];

    [dataTask resume];

    return dataTask;

}

3.HEAD

// 使用HEAD 方法获取数据，

- (NSURLSessionDataTask *)HEAD:(NSString *)URLString

                    parameters:(id)parameters

                       success:(void (^)(NSURLSessionDataTask *task))success

                       failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure

{

    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"HEAD" URLString:URLString parameters:parameters uploadProgress:nil downloadProgress:nil success:^(NSURLSessionDataTask *task, __unused id responseObject) {

        if (success) {

            success(task);

        }

    } failure:failure];

    [dataTask resume];

    return dataTask;

}

4.POST

- (NSURLSessionDataTask *)POST:(NSString *)URLString

                    parameters:(id)parameters

                       success:(void (^)(NSURLSessionDataTask *task, id responseObject))success

                       failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure

{

    return [self POST:URLString parameters:parameters progress:nil success:success failure:failure];

}

- (NSURLSessionDataTask *)POST:(NSString *)URLString

                    parameters:(id)parameters

                      progress:(void (^)(NSProgress * _Nonnull))uploadProgress

                       success:(void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success

                       failure:(void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure

{

    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"POST" URLString:URLString parameters:parameters uploadProgress:uploadProgress downloadProgress:nil success:success failure:failure];

    [dataTask resume];

    return dataTask;

}

5.上传数据

- (NSURLSessionDataTask *)POST:(NSString *)URLString

                    parameters:(nullable id)parameters

     constructingBodyWithBlock:(nullable void (^)(id<AFMultipartFormData> _Nonnull))block

                       success:(nullable void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success

                       failure:(nullable void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure

{

    return [self POST:URLString parameters:parameters constructingBodyWithBlock:block progress:nil success:success failure:failure];

}

- (NSURLSessionDataTask *)POST:(NSString *)URLString

                    parameters:(id)parameters

     constructingBodyWithBlock:(void (^)(id <AFMultipartFormData> formData))block

                      progress:(nullable void (^)(NSProgress * _Nonnull))uploadProgress

                       success:(void (^)(NSURLSessionDataTask *task, id responseObject))success

                       failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure

{

    NSError *serializationError = nil;

    NSMutableURLRequest *request = [self.requestSerializer multipartFormRequestWithMethod:@"POST" URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters constructingBodyWithBlock:block error:&serializationError];

    if (serializationError) {

        if (failure) {

#pragma clang diagnostic push

#pragma clang diagnostic ignored "-Wgnu"

            dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{

                failure(nil, serializationError);

            });

#pragma clang diagnostic pop

        }

        return nil;

    }

    __block NSURLSessionDataTask *task = [self uploadTaskWithStreamedRequest:request progress:uploadProgress completionHandler:^(NSURLResponse * __unused response, id responseObject, NSError *error) {

        if (error) {

            if (failure) {

                failure(task, error);

            }

        } else {

            if (success) {

                success(task, responseObject);

            }

        }

    }];

    [task resume];

    return task;

}

6.PUT

- (NSURLSessionDataTask *)PUT:(NSString *)URLString

                   parameters:(id)parameters

                      success:(void (^)(NSURLSessionDataTask *task, id responseObject))success

                      failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure

{

    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"PUT" URLString:URLString parameters:parameters uploadProgress:nil downloadProgress:nil success:success failure:failure];

    [dataTask resume];

    return dataTask;

}

7.PATCH

- (NSURLSessionDataTask *)PATCH:(NSString *)URLString

                     parameters:(id)parameters

                        success:(void (^)(NSURLSessionDataTask *task, id responseObject))success

                        failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure

{

    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"PATCH" URLString:URLString parameters:parameters uploadProgress:nil downloadProgress:nil success:success failure:failure];

    [dataTask resume];

    return dataTask;

}

8.DELETE

- (NSURLSessionDataTask *)DELETE:(NSString *)URLString

                      parameters:(id)parameters

                         success:(void (^)(NSURLSessionDataTask *task, id responseObject))success

                         failure:(void (^)(NSURLSessionDataTask *task, NSError *error))failure

{

    NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"DELETE" URLString:URLString parameters:parameters uploadProgress:nil downloadProgress:nil success:success failure:failure];

    [dataTask resume];

    return dataTask;

}

9.私有方法

- (NSURLSessionDataTask *)dataTaskWithHTTPMethod:(NSString *)method

                                       URLString:(NSString *)URLString

                                      parameters:(id)parameters

                                  uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgress

                                downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgress

                                         success:(void (^)(NSURLSessionDataTask *, id))success

                                         failure:(void (^)(NSURLSessionDataTask *, NSError *))failure

{

    NSError *serializationError = nil;

    NSMutableURLRequest *request = [self.requestSerializer requestWithMethod:method URLString:[[NSURL URLWithString:URLString relativeToURL:self.baseURL] absoluteString] parameters:parameters error:&serializationError];

    if (serializationError) {

        if (failure) {

#pragma clang diagnostic push

#pragma clang diagnostic ignored "-Wgnu"

            dispatch_async(self.completionQueue ?: dispatch_get_main_queue(), ^{

                failure(nil, serializationError);

            });

#pragma clang diagnostic pop

        }

        return nil;

    }

    __block NSURLSessionDataTask *dataTask = nil;

    dataTask = [self dataTaskWithRequest:request

                          uploadProgress:uploadProgress

                        downloadProgress:downloadProgress

                       completionHandler:^(NSURLResponse * __unused response, id responseObject, NSError *error) {

        if (error) {

            if (failure) {

                failure(dataTask, error);

            }

        } else {

            if (success) {

                success(dataTask, responseObject);

            }

        }

    }];

    return dataTask;

}

这篇文章确实比较简单，有了前几篇文章的铺垫，到了我们真正使用的时候，一切都变得那么简单自然啊.我们已经不知不觉中学到了很多知识，但有一点，知识这东西，要反复的记忆才能记住。举个例子吧，平时可能我们需要在web端查看json数据，当我们把参数拼接到paramter中，该怎么查看呢？

找到AFURLRequestSerialization这个.m
找到requestBySerializingRequest: withParameters: error:这个方法
NSLog(@"URL: %@",mutableRequest.URL.absoluteString);

说明

接下来先把 AFNetworking 的分类再解析完，然后开始搭建网络框架。