创建请求对象

        self.httpUrlSessionManager = [[AFHTTPSessionManager alloc] init];
        [self.httpUrlSessionManager.requestSerializer setValue:@"multipart/form-data" forHTTPHeaderField:@"Content-Type"];
        
        self.httpJsonSessionManager = [[AFHTTPSessionManager alloc] init];
        self.httpJsonSessionManager.requestSerializer = [AFJSONRequestSerializer serializer];
        [self.httpJsonSessionManager.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];

发起请求，比如post请求，调用方法:

- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString
                             parameters:(nullable id)parameters
                                headers:(nullable NSDictionary <NSString *, NSString *> *)headers
                               progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgress
                                success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
                                failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;

上传文件调用方法

- (nullable NSURLSessionDataTask *)POST:(NSString *)URLString
                             parameters:(nullable id)parameters
                                headers:(nullable NSDictionary <NSString *, NSString *> *)headers
              constructingBodyWithBlock:(nullable void (^)(id <AFMultipartFormData> formData))block
                               progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgress
                                success:(nullable void (^)(NSURLSessionDataTask *task, id _Nullable responseObject))success
                                failure:(nullable void (^)(NSURLSessionDataTask * _Nullable task, NSError *error))failure;

如：

[self.httpUrlSessionManager POST:finalUrl parameters:nil headers:nil constructingBodyWithBlock:^(id<AFMultipartFormData>  _Nonnull formData) {
        NSData *fileData = [NSData dataWithContentsOfFile:filePath];
        [formData appendPartWithFileData:fileData name:@"name" fileName:fileName mimeType:@""];
    } progress:^(NSProgress * _Nonnull uploadProgress) {
        if (ccuploadProgress) {
            ccuploadProgress((CGFloat)uploadProgress.completedUnitCount/(CGFloat)uploadProgress.totalUnitCount);
        }
    } success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
        if (success) {
            success(responseObject);
        }
    } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
        if (error && failure) {
            failure(error);
        }
    }];

下载文件：

    NSURL *url=[NSURL URLWithString:urlstring];

    NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:url];
    
    AFHTTPSessionManager *mgr=[AFHTTPSessionManager manager];
    NSURLSessionDownloadTask *task= [mgr downloadTaskWithRequest:request progress:^(NSProgress * _Nonnull downloadProgress) {
        if (cdownloadProgress) {
            cdownloadProgress((CGFloat)downloadProgress.completedUnitCount/(CGFloat)downloadProgress.totalUnitCount);
        }
    }destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {
        return  [NSURL fileURLWithPath:filePath isDirectory:NO];
    } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {
        if(error){
            failure(error);
        }else{
            success(nil);
        }
        
    }];
    [task resume];