更新Xamarin.Android上的通知文本

using Android.App;
using Android.Content;
using Android.OS;
using Android.Support.V4.App;

namespace XamarinAndroidNotificationExample
{
    [Activity(Label = "XamarinAndroidNotificationExample", MainLauncher = true)]
    public class MainActivity : Activity
    {
        private const int NotificationId = 1;
        private NotificationCompat.Builder notificationBuilder;
        private NotificationManager notificationManager;

        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            SetContentView(Resource.Layout.Main);

            // 创建通知渠道（适用于Android 8.0及以上版本）
            CreateNotificationChannel();

            // 创建通知构建器
            notificationBuilder = new NotificationCompat.Builder(this, "channel_id")
                .SetSmallIcon(Resource.Drawable.icon)
                .SetContentTitle("通知标题")
                .SetContentText("初始通知文本");

            // 获取通知管理器
            notificationManager = (NotificationManager)GetSystemService(Context.NotificationService);

            // 发送通知
            notificationManager.Notify(NotificationId, notificationBuilder.Build());
        }

        private void CreateNotificationChannel()
        {
            if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
            {
                var channel = new NotificationChannel("channel_id", "Channel Name", NotificationImportance.Default);
                channel.Description = "Channel Description";
                notificationManager = (NotificationManager)GetSystemService(Context.NotificationService);
                notificationManager.CreateNotificationChannel(channel);
            }
        }

        private void UpdateNotificationText(string newText)
        {
            // 更新通知文本
            notificationBuilder.SetContentText(newText);

            // 重新发送通知
            notificationManager.Notify(NotificationId, notificationBuilder.Build());
        }
    }
}