Introduction to Control and Cell Programming Topics for Cocoa

Controls and cells implement user-interface objects, like buttons, text fields, and sliders.

This topic contains these subtopics:

Button Programming Topics	A user interface object that sends an action message to a target when clicked.
Image View Programming Topics	A user interface object that displays a single image in a frame, and optionally allow a user to drag an image to it.
Slider Programming Topics	A user interface object that displays a range of values and has an indicator, or knob, which indicates the current setting.
Text Fields	A user interface object that displays text that the user can select or edit.
Box Programming Topics	A user interface object that can draw a border around itself and title itself.
Progress Indicator Programming Topics	A user interface object that shows that a lengthy task is under way.
Status Bar Programming Topics	A user interface object that displays a collection of items that provide interaction with or feedback to the user.
Browser Programming Topics	Provides a user interface for displaying and selecting items from a list of data or from hierarchically organized lists of data, such as directory paths.
Matrix Programming Guide	A user interface object used for creating groups of cells that work together in various ways.
Form Programming Topics	A group of related text fields.
Combo Box Programming Topics	A user interface object that gives the user two ways to enter a value: entering it directly in a text field, or choosing it from a pop-up list of pre-selected values.
Table View Programming Guide for Mac	A user interface object that displays data for a set of related records, with rows representing individual records and columns representing the attributes of those records.
Tab View Programming Topics	A user interface object providing a convenient way to provide information in multiple pages.
Outline View Programming Topics	A type of table which lets the user expand or collapse rows containing hierarchical data.
Text Views	Text views are the main user interface objects of the Cocoa text system.
Stepper Programming Topics	A user interface object consisting of two small arrows that can increment and decrement a value that appears beside it, such as a date or time.
Search Fields	A user interface object that provides a standard user interface for searching.
Segmented Control Programming Guide	A user interface object that has the appearance and behavior of a horizontal button divided into multiple segments.

Organization of This Document

Controls and cells implement user-interface objects, like buttons, text fields, and sliders. The control is responsible for

Displaying itself
Intercepting user events (such as a clicking a button or moving a slider)
Sending actions to other objects, usually in response to a user event (such as changing a variable’s value as a slider moves or performing a command when a button is pressed.)

A control usually delegates the first two responsibilities to cells. Splitting these responsibilities off makes it easier to create a control with many identical elements (like a spreadsheet table) or with a few different elements (like a pull-down list that lets you enter a string either in a text field or from a menu of pre-elected strings).

Here are the concepts:

About Cells and Controls gives basic information on what the NSCell and NSControl classes do.
How Controls and Cells Interact gives more information on how controls and cells interact and how they operate.
Cell States describes the three states a control can have: on, off, or mixed. Although used primarily by NSButton, states are defined in NSCell so future subclasses can use them.
Represented Objects explains how to associate a cell with the object it represents.

Here are the tasks:

"Manipulating Cells and Controls" discusses various tips and techniques for dealing with cells and controls.
Changing the Cell for a Control describes how to change the NSCell subclass that a control uses.
Displaying Cell Values describes how some cells format and display their values as strings.
Validating Control Entries describes how to validate the contents of some cells, especially cells in a matrix or text field.
Using a Continuous Control describes how to set up a control so it sends its action message repeatedly while being pressed.
Subclassing NSCell and Subclassing NSControl describe how to create custom subclasses of NSCell and NSControl.
Using the System Control Tint describes how to use the system-wide control tint in your custom views and control cells.