Sorry for such a basic question.
After using MS Visual Studio for 15 years, I recently moved to Apple and its Xcode. So I am really newbie in this new tool. I can work with some very basic parts of utilities as Referencing outlets or such stuff, but there are a lot of other stuff there that I had never seen in Visual Studio (as file owner, accessibility reference, …)
I am looking for a good tutorial on that. Any one knows any? Any suggestions will be appreciated.

This is something like Properties menu in VS. the only difference is that you can simply change to Assistant editor and hold control+drag from each one directly to your code.
Remember this is based on MVC ( Model= data, View= what you see and Controller)
In fact view and model are almost separated and controller is the connector between them:
this may help in the picture above: everything is counted based on Controller: OUT-let can remind you OUT of controller: I mean commands from controller to something. and sender means what sends messages TO the controller. These will make codes just like delegate coding in Visual Studio when you drag and drop an object to the window and double click on them. The (id)sender is counterpart of (void)sender in VS.