This app is a sample app of the open source library Touch Icon Extractor that gets a WebClip icon. Although this is a sample implementation of the library, you can check how the WebClip icon actually set on the website looks from the app.

Details of the library, and source code are below
https://github.com/ohmae/touch-icon-extractor
https://github.com/ohmae/touch-icon-extractor-sample
I think that you can use it widely because it is a MIT license.