NSControlTextDidBeginEditingNotification

NSControlTextEditingDelegate is a protocol in Apple's AppKit that allows an object to respond to and control editing events in controls derived from NSControl, such as NSTextField and NSComboBox. Implementing this protocol enables validation, interception of editing start and end, and reaction to text changes within a text-editing control. The protocol defines a set of optional methods that your delegate can implement as needed.

Common methods

- control:textShouldBeginEditing: returns a BOOL indicating whether editing should begin for the given control and field editor.

- control:textShouldEndEditing: returns a BOOL indicating whether editing should end for the given control and field editor.

- controlTextDidBeginEditing: notifies you when editing begins via an NSNotification.

- controlTextDidEndEditing: notifies you when editing ends via an NSNotification.

- controlTextDidChange: notifies you when the text changes via an NSNotification.

Usage

To use NSControlTextEditingDelegate, declare your class as conforming to the protocol and implement the desired methods. Then assign your object as the delegate of the text control, for example, textField.delegate = self. The should methods can be used to enforce rules (such as character limits or content validation), while the did methods let you react to editing lifecycle events or update related UI.

Notes

All methods are optional, so you implement only what you need. The shouldBegin and shouldEnd editing methods receive the relevant control context and, for the should methods, can inspect the field editor to guide behavior. This protocol works alongside other AppKit text-related delegates to provide fine-grained control over text input.