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Asked: 2026-05-18T07:27:55+00:00

I’m new to Objective-C and the iPhone and thought I was getting the hang

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I’m new to Objective-C and the iPhone and thought I was getting the hang of it until, after many play apps, I ran into a really basic problem around MVCs, NIBs and IB. Are there any really clear explained examples of how to follow this framework that I could go back to?

@interface test1ViewController : UIViewController {

    IBOutlet myView *myview;
    IBOutlet myModel *mymodel;
}

Both the views and models are linked in by IBOutlets but instantiating the model object either kills the application or produces an object which does not respond to any messages.

I am also unclear as to where to carry best out initialisations. I currently do this over viewDidLoad in the view controller. Is there a standard way to do this and does the simulator actually always start up in the same way? Should one use awakeFromNib? Does it make any difference if I use plain code or the IB? And if I have use the IB, should it include a model object?

The MVC idea would make good sense for me here because I have potentially several views and view controllers all feeding back into – and sharing – one common central data model. Any references or advance on this newbie problem would be more than welcome!

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1 Answer

  1. Editorial Team

    IB makes functionality invisible. I don’t like it and I don’t use IB any more, preferring to have everything in code. Then when you look at code you see what is going on – all the navigation controllers, all the formatters etc. – without switching over to IB. Maybe Xcode4 will make it better with integrated IB but I probably won’t go back. Lots of people do like IB so try both methods and see what you like best.

    IBOutlet/IBAction actually mean nothing to the compiler but they let IB recognise the ivars it can send messages to or that will write to elements in a xib. Your use of it here is a bit simplistic unless you really do have a model that only communicates one way with the xib. What you more usually have is a range of controls in the xib linked to the view object, the view communicating directly with the controller. The controller communicates with the model. Very loosely speaking, model is your internal representation of data and logic, view is what you see, controller is the glue between them.

    The MVC line can be fuzzy and you just have to get comfortable with it. If you have a slider control with a value representing some value in your model then it can be hard to think of it as part of the interface especially when you persist the value and use it as a central part of your model. I like the Stanford iPhone class introduction of it. They don’t spend a heap of time on it because it can be difficult to follow exactly and there are situations where it isn’t best.

    Notes from that class – you can find the video on iTunes to follow along.

    Your use of viewDidLoad is correct, that’s your chance to perform initialization on views and their objects. If using IB you will probably not have much to do there because you can set most properties in the xib. If not using IB you will use it a lot more.

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