objective C on how to make connection of two .xib file -

I have been written for two .xib file interfaces. How do the relationship between these two files become? When I run the file, the first .xib will appear, when I click on the button, the second .xib file will appear and the first will be at the top of the .xib file. Thus, I want to use the second .xib function to control the first .xib file. Thus, the two .xib file at the end is how to do this? Thank you.

I'm not sure that I really understand the question, but .xib files should not have a Talk to another. This is what your controller classes have to do.