My transition to a Mac developer was a bit tough. My biggest lament was giving up FlashDevlop on Windows, my favorite code editor for Actionscript and its counterpart for Unity, UnityDevelop.
This didn’t affect me too much until I started my iOS game in Corona SDK, using Lua, and was coding daily. I was using Xcode somewhat happily until an Xcode update disable support for Lua (Thanks Apple!) which left me code editor-less.
I tried about every editor and Lua package I can find and settled on Textmate. While many of the options in Textmate can be a bit difficult to find, it does everything I want it to: projects, smart code completion, that takes into account my defined variables, TODO lists, code snippets, method browser and bookmarks.
I have even jumped on a couple other recommended editors during my development and none of them stand up to Textmate.
So if you are an Actionscript developer making the jump to Corona SDK, buy Textmate, read a few of the docs and I think you will be happy.