Question

I have the following issue:

I want to create a method which accepts input from different subclasses of UITableViewController. If I identify the input as (id) the compiler won’t accept any methods on the custom table view controllers:

-(void)addViewControllerSubview:(id)viewController {
    [viewController customMethod]; //Compiler does not allow this method
}

What is the way to identify the input so that I can use different subclasses of UITableViewController and at the same time my custom methods?

Thanks for any help!

Answer 1

While you can send a message to any object (id) – property accessors require that the compiler be aware of the type you are dealing with – this is because property accessors are syntactic sugar around calling specific getter and setter methods.

Instead of using (id), use the class name (CustomViewController *) to alert the compiler to the class that you’re using.
Another option is to do something like this:

-(void)addViewControllerSubview:(id)viewController {
    CustomViewController *vc = (CustomViewController *)viewController;
    [vc customMethod];
}

Either way, be sure to import the header for the custom class.

EDIT: If you have multiple custom view controllers, the you can use if ([viewController isKindOfClass:[CustomViewController class]])