Keyboard Shortcut Recorder for UIKit

This is a custom control making it easy for record a keyboard shortcut for use with a UIKeyCommand. It is primarily intended for use on iPad. It also works on iPhone when a hardware keyboard is attached.

A sample project demonstrating this is available in a separate repository.

This project is heavily inspired by KeyboardShortcuts by Sindre Sorhus, a library that performs a similar function for macOS. There are some code snippets directly copied from KeyboardShortcuts (with a copy of its license agreement). Unread uses KeyboardShortcuts on macOS, and this library on iPadOS.

Getting started

1. Incorporate via Swift Package Manager.

The GitHub URL is https://github.com/jbrayton/KeyboardShortcutRecorderForUIKit.

2. Implement KEYKeyboardFieldDelegateType.

public protocol KEYKeyboardFieldDelegateType : NSObject {
    
    // Should return true if allowed, false if not. The caller is responsible for
    // giving the user and error message or a warning if returning false.
    // This is asynchronous so that the caller can present an alert that lets the user
    // override a warning.
    //
    // This library assumes that setting the shortcut to nil (clearing the shortcut) is
    // always valid, and therefore that calling `setShortcut(shortcut: nil)` always returns
    // true.
    func setShortcut( shortcut: KEYKeyboardShortcut? ) async -> Bool
    
}

The caller is responsible for storing and using the shortcut as it sees fit. KEYKeyboardShortcut conforms to Codable, making it easy to store.

3. Create the shortcut field.

Create the shortcut:

self.keyboardShortcutField = KEYKeyboardShortcutField()
self.keyboardShortcutField.translatesAutoresizingMaskIntoConstraints = false

// If there is a default value.
self.keyboardShortcutField.shortcut = …
self.keyboardShortcutField.shortcutFieldDelegate = self // (or your delegate of choice)
self.view.addSubview(self.keyboardShortcutField)
self.view.addConstraints([
	…
])

4. Use the shortcut for a UIKeyCommand.

override var keyCommands: [UIKeyCommand]? {
	get {
		var result = [UIKeyCommand]()
		if let shortcut = myShortcut {
			let functionKeyCommand = UIKeyCommand(input: shortcut.input, modifierFlags: shortcut.modifierFlags, action: #selector(handleKeyCommand(_:)))
			result.append(functionKeyCommand)
		}
		return result
	}
}

These are just code snippets. A fully-functional sample project is available.

Notes:

• The control handles light mode and dark mode reasonably by default.
• You can specify your own colors for the text, placeholder text, etc.
• By default, the initial font is UIFont.systemFont(ofSize: UIFont.systemFontSize). The control does not resize itself based on dynamic type size settings. The application is responsible for changing the control’s font value when the type size changes.

Limitations:

• This deliberately only works with a hardware keyboard. Giving this control keyboard focus will not result in the software keyboard appearing.
• The control’s default color scheme looks good, but the colors are not completely consistent with the default colors of a UITextField.

Notes:

• Using function keys as UIKeyCommands does not appear to work on iPadOS. I filed FB15095501. This control will not reject them. I recommend rejecting them in your KEYKeyboardFieldDelegateType implementation.