funkybro
I've stuck to using GWT generated JS in a hidden webview on iOS, rather than J2ObjC.
I've found the process of compiling code on J2ObjC to be difficult and laborious. It may have improved but on initial investigation I ended up hacking a script to try and generate the correct command line for my project. Not to mention downloading and unpacking each library jar by hand.
GWT on the other hand integrates easily with Maven, pulls in all your dependencies and filters out unused methods.
Additionally, the code can be run anywhere else JS is available, in our case Windows Phone and Xbox One.
Cross platform development in Java is compiled to JS via GWT and can be deployed anywhere Java or JS is available.
It powers apps with hundreds of thousands of users on iOS, Android, Windows, Windows Phone and Xbox One.