Example of dynamic iOS UI that changes based on the connection/disconnection of a hardware keyboard, based on suggestions from @JohnRHeaton. Requires linking to private GraphicsServices framework. rdar://problem/15447952

HWKViewController.m

//
//  HWKViewController.m
//  HardwareKeyboardUI
//
//  Created by Steven Troughton-Smith on 13/11/2013.
//  Copyright (c) 2013 High Caffeine Content. All rights reserved.
//

#import "HWKViewController.h"

extern const char* kGSEventHardwareKeyboardAvailabilityChangedNotification; // = "GSEventHardwareKeyboardAttached"
extern BOOL GSEventIsHardwareKeyboardAttached();

static void HardwareKeyboardStatusChanged(CFNotificationCenterRef center, void *observer, CFStringRef name, const void *object, CFDictionaryRef userInfo)
{
    NSLog(@"Darwin notification NAME = %@",name);
	
	[[NSNotificationCenter defaultCenter] postNotificationName:@"HardwareKeyboardStatusChanged" object:(__bridge id)object userInfo:(__bridge id)userInfo];
}

@implementation HWKViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	
	CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(),
                                    NULL, // observer
                                    HardwareKeyboardStatusChanged, // callback
                                    (__bridge CFStringRef)[NSString stringWithUTF8String:kGSEventHardwareKeyboardAvailabilityChangedNotification], // event name
                                    NULL, // object
                                    CFNotificationSuspensionBehaviorDeliverImmediately);
	
	[[NSNotificationCenter defaultCenter] addObserverForName:@"HardwareKeyboardStatusChanged" object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *note) {
		
		if (GSEventIsHardwareKeyboardAttached())
		{
			[self.helloButton setTitle:@"⌘H Hello" forState:UIControlStateNormal];
		}
		else
		{
			[self.helloButton setTitle:@"Hello" forState:UIControlStateNormal];
		}
	}];
	
	[[NSNotificationCenter defaultCenter] postNotificationName:@"HardwareKeyboardStatusChanged" object:nil]; // set initial state
}

#pragma mark -

-(BOOL)canBecomeFirstResponder
{
	return YES;
}

-(NSArray *)keyCommands
{
	return @[[UIKeyCommand keyCommandWithInput:@"h" modifierFlags:UIKeyModifierCommand action:@selector(helloPressed:)]];
}

#pragma mark -

- (IBAction)helloPressed:(id)sender
{
	self.alertView = [[UIAlertView alloc] initWithTitle:@"Hello" message:@"Hello World!" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
	[self.alertView show];
}

@end