AFN 设置请求数据类型

 AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];

        manager.requestSerializer = [AFHTTPRequestSerializer serializer];

        manager.responseSerializer.acceptableContentTypes = [NSSetsetWithObject:@"application/json"]; // 设置content-Type为text/html 或 application/json

        manager.requestSerializer = [AFJSONRequestSerializer serializer];

        manager.responseSerializer = [AFJSONResponseSerializer serializer];

    

        

        [manager POST:GetInstalment parameters: postDics success:^(NSURLSessionDataTask *task, id responseObject) {

            NSLog(@"afn%@", responseObject);

            

        } failure:^(NSURLSessionDataTask *task, NSError *error) {

            NSLog(@"afn%@", error);

        }];