I have read several resources so far about MVC design pattern for iPhone application development. However I have one question related Model part of MVC in iPhone development context.
Firstly, I would like to say what I think of MVC,
Model : is related to a data which we have regarding our application’s objects. Example : Application of a Train simulator than, Each train on simulation will be having it’e own attributes and that will be saved inside Train model.
Controller : is something which controls UI updates. It keeps a reference to Train model and checks for any changes in model, If there is than change the View of that particular train. And it keeps checking for any UI input so it can change data inside Model.
View : This is fairly obvious View is all about UIView, What we see on screen.

Now, Question is…
Does Model has to be persistent to be considered as a Model? or I can
have a Class which has variables without any persistency. Would that
be considered as Model as well, Or Model must be stored somewhere like
in CoreData or .Txt file etc….
Thanks for any input!
It may vary or transform as long as your controller can support it.
Not at all.
You can use any Model if applicable. Model is just another abstraction of your actual logic/database/network access/blablabla…