NSComboBox

NSComboBox is a user interface control in Apple's AppKit (macOS) that combines a text field with a pop-up list of items. It allows users to select from a predefined set of options or, when editable, to type their own text. The control can operate in two modes: non-editable, where input must come from the list, and editable, where typing can either add new text or trigger autocompletion against the available items.

Items can be supplied directly as strings or provided via a data source. When using a data source, the control queries the data source for the number of items and the value for a given index. Alternatively, items can be added, inserted, or removed programmatically through the standard item-manipulation methods. The combo box also exposes properties to retrieve or set the current text value and to check whether editing is enabled.

Interaction and events are handled through a delegate. A common use is to implement the comboBoxSelectionDidChange: method to respond when the user selects a different item. If the control is editable, it can offer autocompletion behavior by matching the partial string against the available items.

NSComboBox is commonly configured in Interface Builder or programmatically within macOS applications. It supports both static item lists and dynamic content via a data source, making it suitable for forms, filters, and settings where a compact, combined input-and-choice control is desirable.