xcode build error ...
当误从project中去除 一些 FrameWork 时候，便会出现 “....referenced from:” 之类的错误，
如当误删 Foundation.Framework 时候，将会出现
“.objc_class_name_NSObject”,reference from:
.objc_class_name_HelloWorldAppDelegate in HelloWorldAppDelegate.o
Synbol(s) not found
Collect2: id returned 1 exit status
http://blog.csdn.net/gsherofly/article/details/8539062 bug调节
