Shows selection of table view cells on pressing the up/down arrow keys.

AppDelegate.m

@implementation AppDelegate

#pragma mark - Key Command Controller

- (KeyCommandController *)keyCommandController {

	if (!_keyCommandController) {
		UIViewController *rootViewController = self.window.rootViewController;
		if (rootViewController){
			_keyCommandController = [[KeyCommandController alloc] initWithRootViewController:rootViewController];
		}
	}

	return _keyCommandController;
}

// Make the KeyCommandController part of the responder chain.
- (UIResponder *)nextResponder {
	return self.keyCommandController;
}

@end

IssuesViewController.m

@implementation IssuesViewController

- (NSArray<UIKeyCommand *> *)keyCommands {
	NSMutableArray<UIKeyCommand *> *commands = [NSMutableArray new];
	[commands addObject:[UIKeyCommand keyCommandWithInput:UIKeyInputUpArrow modifierFlags:(UIKeyModifierFlags)0 action:@selector(selectPreviousIssue:) discoverabilityTitle:@"Select Previous Issue"]];
	[commands addObject:[UIKeyCommand keyCommandWithInput:UIKeyInputDownArrow modifierFlags:(UIKeyModifierFlags)0 action:@selector(selectNextIssue:) discoverabilityTitle:@"Select Next Issue"]];
	return commands;
}

- (IBAction)selectNextIssue:(id)sender {
	[self selectIndexPath:self.nextIndexPath];
}

- (IBAction)selectPreviousIssue:(id)sender {
	[self selectIndexPath:self.previousIndexPath];
}

- (void)selectIndexPath:(NSIndexPath *)indexPath {
	if (!indexPath) return;

	[self.tableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionNone];
	[self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionNone animated:YES];

	UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
	[self performSegueWithIdentifier:@"issue" sender:cell];
}

- (NSIndexPath *)previousIndexPath {

	NSIndexPath *selectedIndexPath = self.tableView.indexPathForSelectedRow;
	if (!selectedIndexPath) {
		return [self lastIndexPath];
	}

	NSInteger selectedRow = selectedIndexPath.row;

	// Loop round to the end
	if (selectedRow == 0) {
		return [self lastIndexPath];
	}

	return [NSIndexPath indexPathForRow:selectedRow - 1 inSection:0];
}

- (NSIndexPath *)nextIndexPath {

	NSIndexPath *selectedIndexPath = self.tableView.indexPathForSelectedRow;
	if (!selectedIndexPath) {
		return [self firstIndexPath];
	}

	NSInteger rows = [self.tableView numberOfRowsInSection:0];
	NSInteger selectedRow = selectedIndexPath.row;

	// Loop round to the start
	if (rows - 1 <= selectedRow) {
		return [self firstIndexPath];
	}

	return [NSIndexPath indexPathForRow:selectedRow + 1 inSection:0];
}


@end

KeyCommandController.swift

import UIKit

public class KeyCommandController: UIResponder {

	public let rootViewController: UIViewController
	public init(rootViewController: UIViewController) {
		self.rootViewController = rootViewController
	}

	// Lets have the this become the first responder and go through all
	// the view controllers and combine all their key commands. We need to make
	// a note of which key commands belong to which view controller so we can
	// provide the view controller in targetForAction(:withSender:) later on.
	// The sender in that case is the key command, so we can just store a
	// dictionary of key commands to view controllers.

	var targets: [UIKeyCommand : UIViewController] = [:]
	override public var keyCommands: [UIKeyCommand]? {

		var commands: [UIKeyCommand] = []
		var targets: [UIKeyCommand : UIViewController] = [:]

		rootViewController.recurseVisibleChildViewControllers { viewController in

			guard let viewControllerCommands = viewController.keyCommands else {
				return
			}

			for command in viewControllerCommands {
				commands.append(command)
				targets[command] = viewController
			}
		}

		self.targets = targets

		return commands
	}

	override public func canBecomeFirstResponder() -> Bool {
		return true
	}

	override public func targetForAction(action: Selector, withSender sender: AnyObject?) -> AnyObject? {

		guard let command = sender as? UIKeyCommand else {
			return nil
		}

		return targets[command]
	}
}