How do I upload files to custom webview?

I am trying to upload files to a Custom WebView, but it either gives me an error or the resulting uri is a number, and it just stops working. Any help is greatly apreciated!

There are suitable blocks provided in the topic you link to.

Otherwise, show you relevant blocks.

sorry for not saying much about my problem, I am trying to make a browser, and I want to be able to upload any file from the phone, selecting it with file explorer.

Please search, maybe you will find something useful.