The Cocoa text system (formerly known simply by the primary class name NSText) is the linked network of

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differently ...

es,

protocol Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

interface Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Int ...

s and

object Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an ...

s that provide

typography Typography is the art and technique of arranging type to make written language legible, readable and appealing when displayed. The arrangement of type involves selecting typefaces, point sizes, line lengths, line-spacing ( leading), an ...

and

text field type=search placeholder=An example text box, which can be used to search the English Wikipedia. A text box (input box), text field or text entry box is a control element of a graphical user interface, that should enable the user to input ...

editing capabilities and to

Cocoa Cocoa may refer to: Chocolate * Chocolate * ''Theobroma cacao'', the cocoa tree * Cocoa bean, seed of ''Theobroma cacao'' * Chocolate liquor, or cocoa liquor, pure, liquid chocolate extracted from the cocoa bean, including both cocoa butter an ...

applications on

Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ancest ...

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...

, where it is the primary text-handling system. Although "extremely complex", the standard text-handling abilities of the Cocoa text system have been widely praised as without peer. It is possible to implement a fully featured rich text editor in only a few lines of code. Formerly embodied in developer NeXT Inc.'s

OpenStep OpenStep is a defunct object-oriented application programming interface (API) specification for a legacy object-oriented operating system, with the basic goal of offering a NeXTSTEP-like environment on non-NeXTSTEP operating systems. OpenStep wa ...

API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...

specification, and implemented in NeXT's

OPENSTEP OpenStep is a defunct object-oriented application programming interface (API) specification for a legacy object-oriented operating system, with the basic goal of offering a NeXTSTEP-like environment on non-NeXTSTEP operating systems. OpenStep wa ...

operating system, and probably also in the earlier

NeXTSTEP NeXTSTEP is a discontinued object-oriented, multitasking operating system based on the Mach kernel and the UNIX-derived BSD. It was developed by NeXT Computer in the late 1980s and early 1990s and was initially used for its range of propri ...

platform, Cocoa's NSText has additionally been implemented via the OpenStep API specification successfully in third-party implementations such as the free-and-open-source

GNUstep GNUstep is a free software implementation of the Cocoa (formerly OpenStep) Objective-C frameworks, widget toolkit, and application development tools for Unix-like operating systems and Microsoft Windows. It is part of the GNU Project. GNUste ...

. The Cocoa text system uses a Model–View–Controller

design pattern A design pattern is the re-usable form of a solution to a design problem. The idea was introduced by the architect Christopher Alexander and has been adapted for various other disciplines, particularly software engineering. The "Gang of Four" boo ...

. The view layer is handled by NSTextView and NSTextField, NSLayoutManager and NSTextContainer are the controller layer, and NSTextStorage (a

mutable In object-oriented and functional programming, an immutable object (unchangeable object) is an object whose state cannot be modified after it is created.Goetz et al. ''Java Concurrency in Practice''. Addison Wesley Professional, 2006, Section 3 ...

attributed string subclass) is the model. The Cocoa text system also interacts with

Services Service may refer to: Activities * Administrative service, a required part of the workload of university faculty * Civil service, the body of employees of a government * Community service, volunteer service for the benefit of a community or a p ...

to provide

standard streams In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin ...

functionality in a GUI environment. Users interact with two classes, NSTextField (providing single-line edit fields) or NSTextView (providing multi-line editing). Each NSTextField uses a shared instance of a NSTextView called the "field editor". This was done to reduce high memory requirements that would arise if every field implemented its own NSTextView

object graph In computer science, in an object-oriented program, groups of objects form a network through their relationships with each other, either through a direct reference to another object or through a chain of intermediate references. These groups o ...

when only one field can actually have

focus Focus, or its plural form foci may refer to: Arts * Focus or Focus Festival, former name of the Adelaide Fringe arts festival in South Australia Film *''Focus'', a 1962 TV film starring James Whitmore * ''Focus'' (2001 film), a 2001 film based ...

at any time. Cocoa adopts many Emacs keybindings familiar to programmers.

References

External links

About the Cocoa Text System
macOS APIs GNUstep {{mac-stub