UWP C# ファイルオープン - Himeyama/himeyama GitHub Wiki

using System;
using Windows.Storage;
using Windows.Storage.Pickers;

namespace App
{
    class Class
    {
        private async void OpenFile(object sender, RoutedEventArgs e)
        {
            FileOpenPicker filePicker = new();
            filePicker.FileTypeFilter.Add(".txt");
            StorageFile file = await filePicker.PickSingleFileAsync();
            string fileName = file.Path;
            text.Text = fileName;
        }
    }
}