Xamarin：NSMutableUrlRequest 和 NSUrlRequest 与 POST 方法和标头和数据？

Question

我有一个 Xamarin 项目，我可以在没有标头的情况下对诸如“reqres.in”API 之类的东西进行 GET 调用：

public Task<string> GetData()
{

    TaskCompletionSource<string> tcs = new TaskCompletionSource<string>();
    NSUrl url = new NSUrl("https://reqres.in/api/users?page=2");
    NSUrlRequest request = new NSUrlRequest(url);
    NSUrlSession session = null;
    NSUrlSessionConfiguration myConfig = NSUrlSessionConfiguration.DefaultSessionConfiguration;
    //config.MultipathServiceType = NSUrlSessionMultipathServiceType.Handover;    //for some reason this does not work!!
    myConfig.MultipathServiceType = (NSUrlSessionMultipathServiceType)2;            //but this works!!
    session = NSUrlSession.FromConfiguration(myConfig);
    NSUrlSessionTask task = session.CreateDataTask(request, (data, response, error) => {
        //Console.WriteLine(data);
        //tell the TaskCompletionSource that we are done here:
        tcs.TrySetResult(data.ToString());
    });

    task.Resume();
    return tcs.Task;

}

但是我尝试了很多变体，但无法使用类似的技术对标头和正文进行 POST 调用。我试过这样：

public Task<string> GetDataFromInternet()
{
    TaskCompletionSource<string> tcs = new TaskCompletionSource<string>();
    NSUrl url = NSUrl.FromString("https://content.dropboxapi.com/2/files/download");

    NSUrlRequest req = new NSUrlRequest(url);
    var authToken = "Bearer my-access-token";
    if (!string.IsNullOrEmpty(authToken))
    {
        NSMutableUrlRequest mutableRequest = new NSMutableUrlRequest(url);

        try
        {
            NSMutableDictionary dic = new NSMutableDictionary();
            dic.Add(new NSString("Authorization"), new NSString(authToken));
            dic.Add(new NSString("Dropbox-API-Arg"), new NSString("{\"path\":\"/path/to/my/file.json\"}"));
            mutableRequest.Headers = dic;

            NSData body = "{\"name\":\"morpheus\", \"job\": \"leader\"}";
            mutableRequest.Body = body;
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }

        mutableRequest.HttpMethod = "POST";
        req = (NSUrlRequest)mutableRequest.Copy();
    }



    NSUrlSession session = null;
    NSUrlSessionConfiguration myConfig = NSUrlSessionConfiguration.DefaultSessionConfiguration;
    myConfig.MultipathServiceType = NSUrlSessionMultipathServiceType.Handover;
    session = NSUrlSession.FromConfiguration(myConfig);
    NSUrlSessionTask task = session.CreateDataTask(req, (data, response, error) =>
    {
//Console.WriteLine(data);
//tell the TaskCompletionSource that we are done here:
tcs.TrySetResult(data.ToString());
    });

    task.Resume();
    return tcs.Task;
}

但这总是返回“无法连接到服务器”。我已经验证，这个带有我的“访问令牌”的 URL 和其他标题和正文数据工作正常。

请告知我可以使这项工作的任何方法。谢谢。

最终修复： 我的代码和“Junior Jiang - MSFT”在解决方案中编写的代码几乎相同。两者都有效，但我发现它们不起作用的真正原因是因为 iOS Bundle Signing 选项中缺少“Entitlements.plist”。由于此文件中包含“多路径 TCP”权利，因此我发现仅选择该选项无济于事。相反，我们必须将其明确包含在“自定义权利”部分中，如下所示：

Answer 1

这是一个关于POST请求的示例代码：

NSUrl nsurl = NSUrl.FromString("Your url adress");//http://www.apple.com/

NSMutableUrlRequest request = new NSMutableUrlRequest(nsurl);
request.HttpMethod = "POST";
NSMutableDictionary dic = new NSMutableDictionary();
dic.Add(new NSString("Content-Type"), new NSString("application/json"));
request.Headers = dic; // add Headers

request.Body = NSData.FromString("{\"version\":\"v1\", \"cityid\": \"101010100\"}"); //add body

NSUrlSession session = NSUrlSession.SharedSession;
NSUrlSessionTask task = session.CreateDataTask(request, (data, response, error) =>
{
    Console.WriteLine("---"+response);
    Console.WriteLine("---"+ data);
    Console.WriteLine("---"+ error);
});
task.Resume();