1、
Undefined symbols for architecture x86_64:
"_OBJC_CLASS_$_LoginReturn", referenced from:
objc-class-ref in LoginViewController.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
在LoginViewController中使用的类LoginReturn没有加入到链接库或没有声明
2、（2015.05.01）
从服务端git pull进行代码合并时的问题：
The operation could not be performed because "ProjectName" has one or more tree conflicts.
I was in trouble with this problem. It often happens when I remove or change the directory of the project .For example, when I move one directory into another existing directory,both of the directory are real folder the warning will exist.
In fact the meaning of tree conflict is that the directory level in your work repository is not same as it was on server.
It's my way to resolve this problem :
- Check which directory in your local work repository differs from the server repository.
- If the local repository has extra directory Delete(local) -> update ->OK , if the local repository lacks of something and the extra elements in server is needless, Delete (server) -> update. NOTE After this the tree conflict is not existing any more.