Imagine that you want to show 1.jpg, which you included using File Manager tab in IDE.
WebView1.LoadHtml ("<img width=100% src=" & QUOTE & xui.FileUri (File.DirAssets, "1.jpg") & QUOTE & ">")
Interesting, why this code works.
In topics dated 5-6 years ago I saw a recommendation to copy pictures from assets to physical folders . Probably, something was changed in IOS.