Issue in Objective -C

[mukyasa]

I followed your tutorial,I created a file WidgetNotification.h and .m,But i when i import the WidgetNotification.h file it gives error

Undefined symbols for architecture i386:
"OBJC_CLASS$_WidgetNotification", referenced from:
objc-class-ref in InterfaceController.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

can u help me out in this?