Why do some XIBs appear to be groups containing other files, and what is the purpose of those files

I think it is a very basic question.Some xib,plist look like a group((see this pic arrow on left)mainwindow.xib,icarou开发者_运维问答selexampleviewcontroller).New.xib file is normal.

what is the difference between this two?

where to use?

what is en?

How to create them?

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It is used for Localization purposes. You can have different nibs based on the language. These just represent the different nibs for different languages. For example consider an app which has a button or image in one of its view, we can have another nib file for the same view for a different language to show the contents of the view in that specific language

go through these links

Link 1

Tutorial

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I guess en is used for localization. It is used when you need to create application in a different language as per client requirement.