When comparing Codea vs UDK, the Slant community recommends UDK for most people. In the question“What are the best 2D game engines?” UDK is ranked 73rd while Codea is ranked 107th. The most important reason people chose UDK is:
UDK has an extremely large toolset that allows creating almost anything without having to use a 3rd party tool or plugin.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Helpful code editor
Errors show up live, as you type. Smarter autocompletion picks up your local and global variables, including nested types. Everything else is just plain smarter, from indentation to highlighting.
Pro Ships with music and sound packs
Codea ships with three great music and sound packs, composed just for Codea and free for you to use in whatever you create.
Pro You can code on an iPad and easily distribute the game
Pro Location library
Location library lets you make use of the GPS inside your iPad. Get your latitude, longitude, altitude and more with a dead-simple API designed specifically for Codea.
Pro Large toolset
UDK has an extremely large toolset that allows creating almost anything without having to use a 3rd party tool or plugin.
Pro Triple A track record
UDK is an engine used by many big name companies for popular games such as the Gears of War series.
Cons
Con Superseded by Unreal Engine 4
Con DevKit only runs on Windows
Even though UDK can deploy games to run on multiple platforms, including Mac, it does not feature support for development on Mac.
Con Limits games to FPS
UDK was originally developed for the FPS, "Unreal Tournament", and it certainly shows. While UDK is a very powerful engine, it takes quite a bit of work to make it do something other than an FPS.