I am using Xcode 4.2 in which I have created various classes which shows various symbols like ?, A, M with the name of the classes. Project is running absolutely fine. Still I'm curious to know the meaning of these symbols. Whether the classes with question mark symbol will create error or warning in future?
After lots of searching I have got the answer at this link under "Keep Track of Your Files’ SCM Status" section.
M = Locally modified
U = Updated in repository
A = Locally added
D = Locally deleted
I = Ignored
R = Replaced in the repository
– = The contents of the folder have mixed status; display the contents to see individual status
? = Not under source control
来源：https://stackoverflow.com/questions/7754850/symbols-meaning-aside-class-name-in-xcode