import Cocoa

class ViewController: NSViewController, NSTextFieldDelegate {
    @IBOutlet weak var textField: NSTextField!
    override func viewDidLoad() {
        super.viewDidLoad()
        textField.delegate = self
    }
    override func controlTextDidEndEditing(_ obj: Notification) {
        DispatchQueue.main.async {
            self.textField.window?.makeFirstResponder(nil)
        }
    }
}