无法向xamarin窗体中的post api调用添加参数

HttpClient client = new HttpClient();

var parameters = new Dictionary<string, string>
{
    { "param1", "value1" },
    { "param2", "value2" }
};

var content = new FormUrlEncodedContent(parameters);

var request = new HttpRequestMessage(HttpMethod.Post, "API_URL");
request.Content = content;

var response = await client.SendAsync(request);

using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Threading.Tasks;

namespace XamarinFormsApp
{
    public class ApiClient
    {
        private readonly HttpClient client;

        public ApiClient()
        {
            client = new HttpClient();
        }

        public async Task<string> PostDataAsync()
        {
            var parameters = new Dictionary<string, string>
            {
                { "param1", "value1" },
                { "param2", "value2" }
            };

            var content = new FormUrlEncodedContent(parameters);

            var request = new HttpRequestMessage(HttpMethod.Post, "API_URL");
            request.Content = content;

            var response = await client.SendAsync(request);

            if (response.IsSuccessStatusCode)
            {
                var result = await response.Content.ReadAsStringAsync();
                return result;
            }

            return string.Empty;
        }
    }
}