AFNetworking 获得header头部的信息 以及添加Content-Type支持的类型

1.在Http请求中， 使用Content-type来指定不同格式的请求信息。在AFNetworking默认支持的类型是有限的，默认支持的类型为@”application/json”, @”text/json”, @”text/javascript”，如果要添加别的类型，例如 application/x-javascript
则该如何做呢？

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.responseSerializer = [AFHTTPResponseSerializer serializer];
manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json",@"text/html", @"text/plain",@"application/x-javascript",nil];

2.AFNetworking获得header头部

[instance POST:urlStr parameters:params progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {


        NSString *time;
        if ([task.response isKindOfClass:[NSHTTPURLResponse class]]) {
            NSHTTPURLResponse *r = (NSHTTPURLResponse *)task.response;
            NSLog(@"%@",[r allHeaderFields]);
        }


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

        [MBProgressHUD hideHUD];
    }];

3.AFNetworing获得编码为GBK(GB2312)的字符串

  NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
        NSString *str = [[NSString alloc] initWithData:result encoding:enc];