====== Xcode Comment Selection ======
I still can't find any built in function to comment/uncomment using // at the beginning of lines.  However, there is a text macro that can be bound to a key combination as follows:
  * open Xcode preferences
  * go to Key Bindings
  * Duplicate a Key Binding Set if you don't already have a custom set
  * expand the Action: Edit -> Insert Text Macro -> C -> Comment Selection
  * double click in the Key column
  * set the key combination of your choice (I suggest Command-/)
  * click Apply/OK
  * now when you select text, press Command-/ to comment the selection using /* and */
  * there is no automated way to uncomment a selection that I know of