Why am I getting "'System.Array' does not contain a definition for 'AsBuffer'" with this WinRT code?

Question

According to this, the following code can be used to convert a byte array into a BitmapImage:

public static async Task<BitmapImage> ByteArrayToBitmapImage(this byte[] byteArray)
{
    if (byteArray != null)
    {
        using (var stream = new InMemoryRandomAccessStream())
        {
            await stream.WriteAsync(byteArray.AsBuffer());
            var image = new BitmapImage();
            stream.Seek(0);
            image.SetSource(stream);
            return image;
        }
    }
    return null;
}

However, I get, "'System.Array' does not contain a definition for 'AsBuffer' and no extension method 'AsBuffer' accepting a first argument of type 'System.Array' could be found (are you missing a using directive or an assembly reference?)"

Is it that the "var stream" assignment is too vague (implicit typing) and I need to specify a particular data type for the "stream" var? Something other than System.Array?

Maybe this, from "Windows Store Apps Succinctly" is a clue: Buffers/byte arrays—System.Runtime.InteropServices.WindowsRuntime. WindowsRuntimeBufferExtensions: Extension methods in this class provide ways for moving between .NET byte arrays and the contents of WinRT buffers, exposed as IBuffer implementations.

...but if it is, that's not enough info for me to know what to do with it. Instead of "TMI" it's "NEI" (Not Enough Information).

Answer 1

The problem is that the compiler isn't finding the extension method AsBuffer(). Make sure you have a reference to the namespace System.Runtime.InteropServices.WindowsRuntime, i.e.

using System.Runtime.InteropServices.WindowsRuntime;

You also need to add a reference to the appropriate DLL, if you haven't already:

Namespace: System.Runtime.InteropServices.WindowsRuntime

Assembly: System.Runtime.WindowsRuntime (in System.Runtime.WindowsRuntime.dll)