Way back in like 2010 there was a clause added briefly to the iOS developer guidelines saying things had to be in Objective-C. There was an outcry and it disappeared not long afterward. Unfortunately, the idea that other languages can't be used persists. Shows how much damage a dumb political mistake can have, even if it's quickly walked back.

They are using this package https://godoc.org/golang.org/x/mobile/cmd/gobind to generate the libraries and bindings for objective c and java.

Couldn't agree more on this. And hopefully there are a enough examples now to show why it simply doesn't work.

If you can't be bothered to fully embrace the design approach of the host platform e.g. Material Design then don't expect your users to be bothered to download your apps. Because most people appreciate that their apps look and feel like a true native app and not some cross platform version that was designed to put the developers first and the users second.