Why CGImageDestination can’t save CGImage?

Short solution for Xamarin.iOS

First, look at the work solution:

var fileUrl = NSUrl.FromFilename(...);
using var img = assetImageGenerator.CopyCGImageAtTime(...);
//...
using (var dest = CGImageDestination.Create(fileUrl, UTType.PNG, 1))
{
    dest.AddImage(img);
    dest.Close();
}

The manual call method Close() is important!

Look at method description:

“Writes the images to the destination and disposes the object.” — Seems so

But Dispose pattern implementation doesn’t support that. Because doesn’t call Close() method.

UPD: GitHub issue: https://github.com/xamarin/xamarin-macios/issues/9058