"Add unimplemented methods" in Xcode like in Eclipse
I don't think it is possible in xcode. You can post an enhancement request here..
You can just type "dash" then "space" and start typing the method name that you want to override. Now push Esc, you will get a list of all possible methods with that string you type. Atleast that reduce the pain of typing full method syntax.
This macrumours thread might be a good read..