Custom UIControlEvents

README.md

The gist is about how to add a custom UIControlEvents. It demonstrates adding a BackSpaceDidPress event, which is fired whenever users tap the backspace keyboard key, to a custom UITextField class. The view controller then listens for the event and do navigation to the previous text field if users press backspace on an empty text field.

MyTextField.swift

struct MyTextFieldEvents: OptionSetType {
    let rawValue: UInt
    static let BackSpaceDidPress = MyTextFieldEvents(rawValue: 1 << 24)
}

class MyTextField: UITextField {

    func addTarget(target: AnyObject?, action: Selector, forControlEvents controlEvents: MyTextFieldEvents) {
        super.addTarget(target, action: action, forControlEvents: UIControlEvents(rawValue: controlEvents.rawValue))
    }

    override func deleteBackward() {
        sendActionsForControlEvents(UIControlEvents(rawValue: MyTextFieldEvents.BackSpaceDidPress.rawValue))
        super.deleteBackward()
    }
}

Usage.swift

class MyViewController: UIViewController {
    @IBOutlet var myPreviousTextField: MyTextField!
    @IBOutlet var myTextField: MyTextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        myTextField.addTarget(self, action: #selector(MyViewController.backSpaceDidTap), forControlEvents: .BackSpaceDidPress)
    }
    
    func backSpaceDidTap(textField: MyTextField) {
        if textField == myTextField && !textField.hasText() {
            myPreviousTextField.becomeFirstResponder()
        }
    }
}