ManualConversationPage.xaml.cs

using Microsoft.Bot.Connector.DirectLine;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace XFChatAppSample.Views
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class ManualConversationPage : ContentPage
    {
        DirectLineClient client;
        string Secret;

        string conversationId = "";
        string responseId = "";
        string watermark = "";

        public ManualConversationPage()
        {
            InitializeComponent();
            Secret = Secrets.DirectLineApiKey;
            client = new DirectLineClient(Secret);
        }

        private async void StartActivity_Clicked(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(conversationId))
            {
                try
                {
                    // クライアントを作成して会話を開始し、ConversationID を取得します。
                    var client = new DirectLineClient(Secret);
                    var conversation = await client.Conversations.StartConversationAsync();
                    conversationId = conversation.ConversationId;

                    ConversationIDLabel.Text = conversationId;
                }
                catch (Exception)
                {
                    throw;
                }
            }
        }

        private async void PostActivity_Clicked(object sender, EventArgs e)
        {
            if (!string.IsNullOrEmpty(conversationId) && !string.IsNullOrEmpty(InputText.Text))
            {
                // ConversationID を指定して会話を開始します。
                var response = await client.Conversations.PostActivityAsync(
                    ConversationIDLabel.Text,
                    new Activity
                    {
                        From = new ChannelAccount("TESTNAME"),
                        Text = InputText.Text,
                        Type = ActivityTypes.Message,
                    });
                responseId = response.Id;

                ResponseIDLabel.Text = responseId;
            }
        }

        private async void GetActivity_Clicked(object sender, EventArgs e)
        {
            if (!string.IsNullOrEmpty(conversationId) && !string.IsNullOrEmpty(responseId))
            {
                // ConversationID を指定して、Activity（複数）を取得します。
                // 毎回 ActivitySet の Watermark が更新されるのでそれを指定することで最新のやり取りを取得できます。
                var activities = await client.Conversations.GetActivitiesAsync(conversationId, watermark);
                watermark = activities.Watermark;
                var result = activities.Activities.LastOrDefault(x => x.ReplyToId == responseId);

                ConversationLabel.Text = result.Text;

                // 取得できる Activity の確認用
                var sb = new StringBuilder();
                foreach (var item in activities.Activities)
                {
                    sb.Append($"Channel ID: {item.ChannelId}\nID: {item.Id}\nReplyToID: {item.ReplyToId}\nText: {item.Text}\n");
                }
                await DisplayAlert("Activities", sb.ToString(), "OK");
            }   
        }
    }
}