New iOS sdk can not build

My ver is 5.3.1f1, when I use the new Xcode to build a iOS app, there is a error say"Unknow type name '__declspec". This error is on file ‘il2cpp-codegen.h’.

This has been corrected in newer versions of Unity. Xcode 7.3 changed the support for some C++ attributes that il2cpp.exe was using in generated code. Please get the 5.3.2f1 release of Unity or later for this correction:

http://unity3d.com/get-unity/download/archive