Today just now I have caught a strange error:duplicate symbol objc ivar...
I don't find the error in the code,and I searched in the internet, SFOers give out some reason like this:
1) same with system's name
2) implement one same .m file twice or more
3) import .m file
4) compile resource twice or more
They are all correct,and I have caught is the 4) one,and I have caught it before I just remember that,oh,shit! Hope I can fix it in one second if I caught it again.