Have you tried to do it both with libraries and frameworks ? And you seem to already have a reference example, please don't ask for step-by-step instructions but instead ask for help at specific steps that you are doing.
Ok, .xib files are the same as any other files, the libraries do not carry resources but have you tried to create a simple framework, add some resources, build framework and check where the resources appear ? And what about resource bundles, did you try to create one for your library ?
No, it is not possible to include xibs inside a static library/framework. You should create a bundle target that will contain all the xibs, image assets, etc that the library will need. In your library, you must then reference the resources from this bundle.
.xibfiles are the same as any other files, the libraries do not carry resources but have you tried to create a simple framework, add some resources, build framework and check where the resources appear ? And what about resource bundles, did you try to create one for your library ?