Converting a category on UIViewController into a custom subclass

Question

I had a class category that adds some methods to UIViewController. I needed to add some instance variables to the category, so I turned it into a custom UIViewController subclass, and added the instance variables. I then turned the UIViewController I was displaying into an instance of the new subclass.

Now I'm having trouble loading the new UIViewController when the application loads. I load the view controller from a nib in my AppDelegate:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        self.viewController = [[ATFIPresentationViewController alloc] initWithNibName:@"ViewController_iPhone" bundle:nil];
    } else {
        self.viewController = [[ATFIPresentationViewController alloc] initWithNibName:@"ViewController_iPad" bundle:nil];
    }
    self.window.rootViewController = self.viewController;
    [self.window makeKeyAndVisible]; //Crashes Here
    return YES;
}

After doing so, an exception is thrown when I call makeKeyAndVisible on my application's window:

Terminating app due to uncaught exception 'NSUnknownKeyException', reason:
'[<ATFIPresentationViewController 0x6c497d0> setValue:forUndefinedKey:]: 
this class is not key value coding-compliant for the key basicPicker.'

Where basicPicker is an IBOutlet to a UITextField. This is happening for every IBOutlet I've defined in my viewController. Why would making my viewController a subclass of my subclass of UIViewController, prevent anything loading from my nib? The "Files Owner" in the nib is ViewController, not ATFIPresentationViewController.

EDIT: Well, I got tired of trying to get this to work the "proper" and less typing heavy way. I got it to work by turning the extension into an NSObject, and pass the UIViewController to it. I posted what I was using this for on gitHub if anyone wants to take a look.

Possible duplicate of this question: http://stackoverflow.com/questions/3088059/this-class-is-not-key-value-coding-compliant-for-the-key — jonkroll, Aug 12 '12 at 17:37
Nope, I saw that already. The class of file's owner is "ViewController" not UIViewController. And none of the IBOutlets have a name like "string". — Brandon Mcq, Aug 12 '12 at 18:01

score 0 · Answer 1 · answered Aug 12 '12 at 22:32

That error is occurring because your nib is trying to set a value onto an instance of a class that doesn't have a property by the name basicPicker. This is a solid indication that you're sending messages to the wrong type of object.

You need set the class of your File's Owner in your nib files to be the new UIViewController subclass you have created and not just the default UIViewController. Select File's Owner in your nib and you can change it in the right panel 'Utilities' third tab named Identity Inspector in Xcode, right at the top.

Converting a category on UIViewController into a custom subclass

1 Answers1