J2ObjC: A Java to iOS Objective-C translator

It appears to work on Java code, not JVM bytecode (similar to GWT), so you'd have to decompile/disassemble the JVM bytecode first.

IT appears to follow GWT in other ways as well such as JSNI-ish interface (can even combine JSNI and native ObjC) and some optimized runtime classes for the ObjC environment.