KdanCommon/Helpers/Base64Helper.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.Storage.Streams;
using Windows.Storage;

namespace KdanCommon.Helpers
{
    public static class Base64Helper
    {
        // https://stackoverflow.com/questions/18553691/metro-getting-the-base64-string-of-a-storagefile/18555063
        public static async Task<string> StorageFileToBase64(StorageFile file)
        {
            string base64String = "";
            if (file != null)
            {
                using (IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.Read))
                {
                    using(var reader = new DataReader(fileStream.GetInputStreamAt(0)))
                    {
                        await reader.LoadAsync((uint)fileStream.Size);
                        byte[] byteArray = new byte[fileStream.Size];
                        reader.ReadBytes(byteArray);
                        base64String = Convert.ToBase64String(byteArray);
                    }
                }
            }
            return base64String;
        }
    }
}