I've got a simple question. In Xcode 3 I was able to lock a file by clicking on the little lock icon at the top of each file. I'm missing this function in Xcode 4. I think I'm just blind. Can you help me?
That feature was killed (partially) in Xcode 4. Even though you can Unlock a locked file from the File menu, you cannot Lock it.
Even though locking files is still possible with the Finder, it is much more troublesome when you need to lock multiple files. The long way now involves right clicking the file in the Project Navigator and selecting Show In Finder. Using Get Info (Cmd-I) will allow you to select Locked. When you do this, the lock symbol will appear in the top-right corner of the source editor, which you can click to Unlock the file.
(It seems there are many features missing in the newer Apple software, including the Hex color values in the Digital Color Meter utility.)
来源：https://stackoverflow.com/questions/5843033/lock-file-in-xcode-4