Putting a category on model classes to specialize UI/layout code for each model type

gistfile1.m

// In MyViewController.m

@interface BaseModelClass (MyViewControllerLayout)

// If your model classes don't have a common superclass, put
// this category on NSObject instead

- (void)layoutForMyViewController:(MyViewController *)controller;

@end

@implementation ModelA (MyViewControllerLayout)

- (void)layoutForMyViewController:(MyViewController *)controller
{
    // layout ModelA object for MyViewController
}

@end

@implementation ModelB (MyViewControllerLayout)

- (void)layoutForMyViewController:(MyViewController *)controller
{
    // layout ModelB object for MyViewController
}

@end

@implementation ModelC (MyViewControllerLayout)

- (void)layoutForMyViewController:(MyViewController *)controller
{
    // layout ModelC object for MyViewController
}

@end

@implementation MyViewController

- (void)someLayoutMethod
{
    for (BaseModelClass *modelObject in self.modelObjects)
    {
        [modelObject layoutForMyViewController:self];
    }
}

@end