controlTextDidBeginEditing

controlTextDid... refers to a group of delegate methods in the macOS AppKit framework used to monitor edits in text controls. These methods are part of the NSControlTextEditingDelegate protocol and are designed to let a controller respond to changes in text fields, text views, and other controls that support editing. The most commonly used methods are controlTextDidBeginEditing:, controlTextDidChange:, and controlTextDidEndEditing:. Each method receives a Notification object whose object property is the NSControl that sent the event.

To use these methods, a class must conform to NSControlTextEditingDelegate and be assigned as the delegate of the text control, typically by setting textField.delegate = self or by connecting it in Interface Builder. The controlTextDidChange: method is called whenever the control’s text changes, such as after a keystroke or a programmatic update. This makes it suitable for real-time validation, enabling or disabling other UI elements, live formatting, or updating dependent state as the user types.

In addition to delegate methods, there are corresponding notifications that can be observed via NotificationCenter: NSControlTextDidBeginEditingNotification, NSControlTextDidEndEditingNotification, and NSControlTextDidChangeNotification. Observing these can be useful when multiple objects need to react to text editing events without implementing the delegate methods themselves.

Notes: these delegates and notifications are specific to macOS AppKit. On iOS, similar functionality is achieved with UITextFieldDelegate methods or UIControl events such as editingChanged.