I'm happy with this method of moving models around in segues. For every model that might move around, a protocol is created for assignment, and a segue category method is added to assign it to destination view controllers if they conform to it. `prepareForSegue:` sends a messages for all its models to any segue.

UIStoryboardSegue+Assignable.m

/***
 *
 * Usage:
 *   ```
 *   - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
 *   {
 *       [segue prepareWithExampleModel:self.model];
 *   }
 *   ```
 */

#import "ExampleModelAssignable.h"


@implementation UIStoryboardSegue (Assignable)

- (void)prepareWithExampleModel:(ExampleModel *)model
{
    UIViewController *destination = [self viewControllerForAssignment];
    
    if ([destination conformsToProtocol:@protocol(ExampleModelAssignable)]) {
        id<ExampleModelAssignable> vc = (id<ExampleModelAssignable>)destination;
        [vc setExampleModel:model];
    }
}

- (UIViewController *)viewControllerForAssignment
{
    if ([self.destinationViewController isKindOfClass:[UINavigationController class]]) {
        return ((UINavigationController *)self.destinationViewController).topViewController;
    }
    else if ([self.destinationViewController isKindOfClass:[UISplitViewController class]]) {
        return ((UISplitViewController *)self.destinationViewController).viewControllers.firstObject;
    }
    else {
        return self.destinationViewController;
    }
}

@end