Question

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Understanding Model-View-Controller

I have a general programming question about how to divide up my code, usually (and I’m trying to get away from this) I just write it all in the viewController, lots and lots of code in the view controller. But now i’ve reviewed some information on the MVC but I have some questions.

My Question

Mainly, if I a view controller (holding a model and a view), and in the model I run a method figures out a number display for the view, so just a simple int which the view would take and display on the screen. In order for my model to tell my view to do this should I go straight from model —-> view. Or should I return the data back to the controller and then send it to the view?

Lastly, if I need to send the data back to the controller, how might I do so, because I thought that the model should’nt know about the controller, only vice-versa.

Sorry for the lengthy question. Thanks for all your help.

Answer 1

There’s a lot of info about this in the net. From Wikipedia:

Though MVC comes in different flavors, control flow is generally as
follows:

1. The user interacts with the user interface in some way (for
   example, by pressing a mouse button).

2. The controller notifies the model of the user action, possibly
   resulting in a change in the model’s state. (For example, the
   controller updates the user’s shopping cart.)

3. A view queries the model in order to generate an appropriate user
   interface (for example the view lists the shopping cart’s contents).
   The view gets its own data from the model. In some implementations,
   the controller may issue a general instruction to the view to render
   itself. In others, the view is automatically notified by the model of
   changes in state (Observer) that require a screen update.

4. The user interface waits for further user interactions, which
   restarts the control flow cycle.

The goal of MVC is, by decoupling models and views, to reduce the
complexity in architectural design and to increase flexibility and
maintainability of code. MVC has also been used to simplify the design
of Autonomic and Self-Managed systems