Question

I have a view controller which contains a scroll view. Inside the scroll view there is another UI core graphics view. In the view controller I create a temp object for the core graphics view and assign some data to it, then assign it to the attribute of the view controller. Eg: In the view controller:

@interface controller : UIViewController {
        GraphView *graph;
}
@property ... IBOutlet GraphView *graph;

@implementation
GraphView *temp = [[GraphView alloc] init];
temp.someArray = anExistingDataArray;
self.graph = temp;

In IB, I open the view controller nib and add a scroll view, and embed a view and assign it the core graphics view class. Then hook up the IBOutlet from that view to the attribute in the view controller.

My problem is that the view controller creates the temp view object, assigns it to itself, with the correct data, however IB seems to instantiate its own object (different memory ID) and displays that, instead of the one in the view controller.

What is the correct way to build this type of setup?

Answer 1

If you drag an object into a nib, IB creates and archives that object. This is why you don’t have to alloc/init views that you create in IB.

I’m guessing that you are creating your view in IB so that you can get the geometry correct, or…? It’s rather unusual to create a view and then immediately replace it at run-time. More common, for geometric purposes, is to create a container view in IB and then add your programmatically-created views as subviews of that.

Your code left out the most important piece of this, though, which is when it’s getting run. Is it in -init…? -awakeFromNib? -loadView? -viewDidLoad? The exact location matters since these occur in a well-defined sequence. If you put your code in the wrong place, it will run before the nib is unarchived and fully reconnected, so the nib will clobber whatever your code did.

So: when is your [self setGraph] (I can’t bring myself to use dot syntax) code getting run?