我想建立并研究Apple的演示项目Son of Grab。
我下载了存档并使用Xcode 6.1打开了项目。构建它失败，错误：
Undefined symbols for architecture x86_64:
"_ChangeBits", referenced from:
-[Controller awakeFromNib] in Controller.o
-[Controller toggleOffscreenWindows:] in Controller.o
-[Controller toggleDesktopWindows:] in Controller.o
-[Controller toggleFramingEffects:] in Controller.o
-[Controller toggleOpaqueImage:] in Controller.o
-[Controller toggleShadowsOnly:] in Controller.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
我尝试将基本SDK更改为10.6然后更改为10.7，希望代码依赖于过时的SDK。但是它仍然会出现相同的错误。