Caleb Davenport has a great post on using UIKeyCommand to implement hardware keyboard shortcuts (now a broken link).

Beside its intended use, UIKeyCommand also presents a great way for you to add debugging shortcuts — that you remove when you ship — to your app. For example, you can assign a shortcut to print out the model details of your current screen or to run -exerciseAmbiguityInLayout if you use Auto Layout.

#ifdef DEBUG
//Subclass of UIResponder
- (BOOL)canBecomeFirstResponder {
    return YES;
}

- (NSArray *)keyCommands {
    return @[
        [UIKeyCommand keyCommandWithInput:@"+" modifierFlags:0 action:@selector(callExerciseAmbiguityInLayoutRecursively)],
        [UIKeyCommand keyCommandWithInput:@"-" modifierFlags:0 action:@selector(displayModelData)],
    ];
}
#endif

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