使用XCode6打开项目以后再用XCode5出现的问题fatal error: malformed or corrupted AST file: 'Unable to load module

使用不同版本的XCode出现的问题：

fatal error: malformed or corrupted AST file: 'Unable to load module "/Users/xxx/Library/Developer/Xcode/DerivedData/ModuleCache/XYZYIE6ZV0OP/Darwin.pcm": file not found' note: after modifying system headers, please delete the module cache at '/Users/me/Library/Developer/Xcode/DerivedData/ModuleCache/XYZYIE6ZV0OP' 1 error generated.fatal error: malformed or