如何在Xcode 4.5中向项目添加对FORTRAN代码的调用？

My company has a bunch of Fortran code. Traditionally, we compiled the code we needed into a .dll and called that .dll when we needed a calculation done. We are now trying to create an iPad app, which unfortunately means we can't just call a .dll anymore. My company has a bunch of Fortran code. Traditi