CODEWITHSUNDEEP
iphoneobjective-cdesign-patterns
Brian Halpin
Brian Halpin

Reputation: 179

Which design pattern to use for a 2D iPhone game?

To give a little background about the game: falling items float from the top, and the objective is to flick/slide another object to hit them. If an item hits the ground, you lose a life, and gain points for hitting falling items.

Here is where I'm a little confused. In O'Reilly's iPhone game development. They state have the AppDelegate inherit a game state machine object, and have the main game loop in the App Delegate. Nothing about MVC.

I was going to use MVC. I have all the objects identified for the models, and was going to use one controller to update each model and their corresponding view. Then have a navigation controller in the App Delegate, and push certain controllers (Play, instructions, stats) from the home screen. Then have the game loop run in my gameViewController. I am using Chipmunk as a physics engine by the way.

This is my first game so I'm little confused. I would greatly appreciate any advice on how to proceed. I would like to get the object orientated design right from the start before jumping into code.

Upvotes: 3

Views: 1804

Answers (3)

TurqMage
TurqMage

Reputation: 3321

My MVC goes something as follows. Each Game Object that is create is just a single Model. Empty data with no logic attached. When the object is created it also gets a Brain or controller attached to it. Each created Brain is added to the Brain list. The Brain List updates each brain and the brains change the Model.

To show something on screen the Brain adds the Model to the Scene. The scene keeps a list of all the models it is rendering. The Scene is also Updated from the Game Loop. Each update the Scene looks at each Model, any model without a View, is given a view (a new view is created based on data in the model). The Scene then tracks the view until the Model's data says it no longer needs it.

When I have been working on the iPhone I like to break the game loop out onto its own thread. Those folks over at O'Reilly are pretty smart though so take what I've got to say with a grain of salt. 

[NSThread detachNewThreadSelector:@selector(GameLoop:) toTarget:self withObject:nil];

Then the game loop itself is updating first the Brains (or "Controller List"), then the Scene (or "view list").

The final piece that ties it all together is the input. For iPhone I use a full screen View. In the touchesBegan and touchesEnd of the view I generate Events which I pass off to the InputManager. The InputManager will send events to different models as needed.

Upvotes: 1

Caleb
Caleb

Reputation: 125037

Do you not consider that game state machine to be a kind of data model? I don't have the O'Reilly book you mention, but the description you give sounds to me very much like MVC.

The main point of MVC is to separate an application's content from the way that content is represented on the screen. The "model" in MVC doesn't have to consist of dumb data objects that you read from a file or a web server... it could just as easily be a simulation, a connection to another device, etc. The way I think of it is that the model is the part that you'd keep if you were going to throw out app's GUI and replace it with a script, a command line interface, or maybe a web service. A game state machine could certainly fit that description.

It's not uncommon in an iOS app to have the application delegate instantiate the model. You then have view controllers that know how to talk to the model and translate the data that it provides into something that can be displayed in the view(s). If some of the data that the model provides are graphic elements like textures or meshes, that's okay... those are the data that the game operates on, after all.

Upvotes: 0

Ryan Bennett
Ryan Bennett

Reputation: 3432

I don't think MVC is really what you want here. MVC could apply to your overall application state - ie a view for the menu, a view for the gameboard etc. It doesn't fit well WITHIN the game play - at least just thinking off the top of my head.

Take a look at this post on gameDev. Lots of useful patterns from people smarter about this than I.

https://gamedev.stackexchange.com/questions/4157/what-are-some-programming-design-patterns-that-are-useful-in-game-development

Upvotes: 7

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