Advice on setting up objective c program - fundamentals

Question

Hi, I've been learning objective-C via a book and tutorials and while I've learned a lot and can do much of what I want, I still struggle to get the basic structure of my programs correct. Here's a specific thing I want to do, but I end up getting lost and confused.

I want to generate a card object that (I think) should be a subclass of UIView. I want to be able to make a new card, set it's frame size and put some subviews in it. I also want to be able to make it change size and move.

I can make a UIView do some of these things and animate the with a block, but I get confused about where to put the pieces of code. I start with a view based template and make a new subclass of UIView. I'd like to have the view controller ask for cards and be able to take user input to manipulate the card. I can make buttons and connect them to IBActions fine, but should I put the change size and move methods in the card object or in the view controller? I want to be able to say something like: declare a new card - tell the card to "move here" when the button's pressed, etc.

I know this may sound like a really generic question, and I'm not looking for someone to write my code for me, but I'd just like some general (or specific!) advice.

Answer 1

Generally speaking, your software should follow the model-view-controller pattern.

Translated, this probably means that the what of the View should be stored in the view. i.e. the picture for the face of the card, the card's value, etc.

Everything having to deal with logic about the card, where it goes, what happens to it, etc. should be placed in the controller.

Finally, a "Deck" class which contains cards and additional logic on them in regards to sorting, shuffling, dealing, etc. should be handled separately in the model.

Ideally this is how the program flow works:

1. User presses View's button
2. View is connected to a method in the controller
3. Controller evaluates the state of the program, and calls a method in the model (like deal)
4. The model performs some logic and returns information
5. the Controller evaluates the return from the model, and updates the view
6. The view redraws itself based on the new update from the controller

It's a pretty basic explanation, but hopefully good enough to keep you out of trouble. I strongly suggest reading Apple's MVC documentation.

Answer 2

Thanks for the advice, Stephen. I have been reading through the MVC documentation and trying to absorb it but it's a lot!

Let me explain the parts of my app so far and see if you think I have them doing the right things...

I made a view based app to start with called FlashCard, so I got a viewConroller (object?) for free and a .xib as well. From what I understand, this encapsulates both my view and my controller. So here's my structure, I think:

Conroller - FlashCardViewController Has action methods for the buttons in my .xib file

View - .xib Has buttons for requesting a new deck of cards for each basic math operator as well as getting a new card from the current deck, and fields for displaying my flashcard info (operands, operator, result)

Model - Card A subclass of UIView. This has properties for the operands, etc., plus the stuff it inherits from UIView. - Deck A subclass of NSObject. This has a single property called cards which is an NSMutableArray. It has a method for generating a deck of cards with all possible operand values based on an operator that comes from the button title. If you click the + button, it makes a deck of + flash cards. It also has a method to select a card from a deck - you pass the deck to it and it returns a random Card object and removes the Card from the Deck.

This all works fine - I can generate new decks and get a card. I then made the Card's initWithFrame method define a frame and when I get a new card from the current deck in the controller, I add the card's view to the controller's view. It shows up fine.

My questions now are - If I want to make the card move somewhere else in the view, should that method be in the controller? or Deck? or Card? Do I have the parts in the right places? When I generate a new Card object (by selecting it from a deck) in the controller via an IBAction method, can I access that card in another method in the controller - will it be available? For example if I made another button that was to move the card across the screen...

Thanks for reading my wordy reply! Any advice is still appreciated!