如何检测可可中单击哪个NSTextField？

Question

I have two NSTextField objects which I want to highlight when user clicks on it.

The initial text field is already highlighted on NSWindow load. I am able to get mouse down event for text field click, but unable to distinguish which textfield did the user tapped.

I tried using hitTest on the text field using the NSPoint obtained from the NSEvent object, but the NSView returned is nil. The view it returns is that of the window's view and not that text field.

class SettingsViewController: NSViewController {
    private var sview: SettingsView?

    override func viewDidLoad() {
        initEvents()
    }

    override func loadView() {
        if let settingsView = SettingsView.createFromNib() {
            self.view = settingsView
            self.sview = settingsView as? SettingsView
        }
    }

    func initEvents() {
        self.sview!.emailTextField.delegate = self
    }

}

extension SettingsViewController: NSTextFieldDelegate, NSTextDelegate {
    override func mouseDown(with event: NSEvent) {
        self.log.debug("mouse down: \(event.buttonNumber), \(event.eventNumber), \(event.locationInWindow)")
        // How to know which text field triggered this?
    }

    func control(_ control: NSControl, textView: NSTextView, doCommandBy commandSelector: Selector) -> Bool {
        self.log.debug("control delegate")
        return false
    }

    func textField(_ textField: NSTextField, textView: NSTextView, shouldSelectCandidateAt index: Int) -> Bool {
        self.log.debug("text field should select")
        return true
    }

    func textShouldBeginEditing(_ textObject: NSText) -> Bool {
        self.log.debug("text field should being editing")
        return true
    }
}

class SettingsView: NSView {
    private let log = Logger()
    private static var topLevelObjects: NSArray?
    @IBOutlet weak var emailTextField: ASTextField!
    @IBOutlet weak var passwordTextField: NSSecureTextField!

    // ...
}

I am adding delegate to only one text field.

self.sview!.emailTextField.delegate = self

But when I click on the passwordTextField , I am getting the mouse click event as well. Why is this happening?

How to distinguish NSTextField mouse click and highlight the text field?

---

I tried subclassing NSTextField and adding click handler, but it is not working.

class ASTextField: NSTextField {
    private let log = Logger()

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        bootstrap()
    }

    override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)
        bootstrap()
    }

    override func awakeFromNib() {
        super.awakeFromNib()
        bootstrap()
    }

    func bootstrap() {
        self.delegate = self
    }
}

extension ASTextField: NSTextFieldDelegate {
    override func mouseDown(with event: NSEvent) {
        // This is not working
        self.log.debug("mouse down")
        super.mouseDown(with: event)
    }
}

Answer 1

The method you overwrote, mouseDown(with) , isn't a member of the NSTextFieldDelegate or NSTextDelegate protocols. You overwrote NSViewController.mouseDown(with) .

Whenever that method is called, the thing that was clicked is your SettingsViewController 's view.

To react to your textfield being selected, you use NSTextFieldDelegate .textField(_:textView:shouldSelectCandidateAt:) , which you already have. The value of the textView parameter is the text view that was selected.

Answer 2

I updated the ASTextField as below.

class ASTextField: NSTextField {

    // ...

    override func mouseDown(with event: NSEvent) {
        self.sendAction(#selector(didClick(_:)), to: self)
        super.mouseDown(with: event)
    }

    @objc func didClick(_ event: NSEvent) {
        self.log.debug("did click")
    }
}

In the SettingsView , I missed calling super.layout() , without which the click won't work, nor the other text field will get focus when clicked.

class SettingsView: NSView {
    // ...

    override func layout() {
        self.log.debug("layout method")
        super.layout()  // This is important
    }
}

NSTextField delegate methods are not required.

Answer 3

If what you're looking for is to be able to select the text when you click (focus) the text field, you can override the class to simplify your task and you won't have to worry about locating the clicked field from the delegate.

For an NSView object, when it gets focus (ie. clicking or tabbing) it will call becomeFirstResponder so we can hook in there.

When an NSTextField becomes editable (or selectable) it grabs a reusable 'field editor' and overlays it on top of your text field during the editing. If your NSTextField has focus, you can grab this field editor using the currentEditor() call on the view.

So, once you have the field editor, you can perform selectAll on the editor to select the text.

Example class :-

class AutoselectOnFocusTextField: NSTextField {
    override func becomeFirstResponder() -> Bool {
        guard super.becomeFirstResponder() else {
            return false
        }
        if let editor = self.currentEditor() {
            editor.perform(#selector(selectAll(_:)), with: self, afterDelay: 0)
        }
        return true
    }
}

Hope this helps!