Undefined symbols for architecture arm64:
"_OBJC_CLASS_$_UIResponder", referenced from:
_OBJC_CLASS_$_AppDelegate in AppDelegate.o
"_OBJC_METACLASS_$_UIResponder", referenced from:
_OBJC_METACLASS_$_AppDelegate in AppDelegate.o
"_UIApplicationMain", referenced from:
_main in main.o
"_OBJC_METACLASS_$_UIViewController", referenced from:
_OBJC_METACLASS_$_LoadingViewController in LoadingViewController.o
"_OBJC_CLASS_$_UIViewController", referenced from:
_OBJC_CLASS_$_LoadingViewController in LoadingViewController.o
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Undefined symbols for architecture arm64:
原文：http://www.cnblogs.com/royi123/p/5482867.html