Editing MacOS (section)

=== Software compatibility ===
{{See also|List of Mac software}}

Apple offered two main [[Application programming interface|APIs]] to develop software natively for macOS: [[Cocoa (API)|Cocoa]] and [[Carbon (API)|Carbon]]. Cocoa was a descendant of APIs inherited from [[OpenStep|OPENSTEP]] with no ancestry from the [[classic Mac OS]], while Carbon was an adaptation of classic Mac OS APIs, allowing Mac software to be minimally rewritten to run natively on Mac OS X.<ref name="Rhapsody and Blues"/>

The Cocoa API was created as the result of a 1993 collaboration between [[NeXT]] Computer and [[Sun Microsystems]]. This heritage is highly visible for Cocoa developers, since the "NS" prefix is ubiquitous in the framework, standing variously for '''N'''eXT'''S'''TEP or '''N'''eXT/[[Sun Microsystems|'''S'''un]]. The official OPENSTEP API, published in September 1994, was the first to split the API between Foundation and ApplicationKit and the first to use the "NS" prefix.<ref name="nextstep_history">{{Cite web |title=Cocoa Fundamentals Guide: A Bit of History |url=https://developer.apple.com/legacy/library/documentation/Cocoa/Conceptual/CocoaFundamentals/WhatIsCocoa/WhatIsCocoa.html#//apple_ref/doc/uid/TP40002974-CH3-SW12 |access-date=January 18, 2018 |website=ADC Reference Library |publisher=[[Apple Developer Connection]] |archive-date=March 7, 2016 |archive-url=https://web.archive.org/web/20160307154056/https://developer.apple.com/legacy/library/documentation/Cocoa/Conceptual/CocoaFundamentals/WhatIsCocoa/WhatIsCocoa.html#//apple_ref/doc/uid/TP40002974-CH3-SW12 |url-status=live}}</ref> Traditionally, Cocoa programs have been mostly written in [[Objective-C]], with Java as an alternative. However, on July 11, 2005, Apple announced that "features added to Cocoa in Mac OS X versions later than 10.4 will not be added to the Cocoa-Java programming interface."<ref>{{Cite web |title=Introduction to Cocoa-Java Integration Guide |url=https://developer.apple.com/legacy/mac/library/#documentation/Cocoa/Conceptual/LanguageIntegration/LanguageIntegration.html |url-status=live |archive-url=https://web.archive.org/web/20090831202711/https://developer.apple.com/legacy/mac/library/#documentation/Cocoa/Conceptual/LanguageIntegration/LanguageIntegration.html |archive-date=August 31, 2009 |access-date=April 8, 2006 |website=ADC Reference Library |publisher=[[Apple Developer Connection]] |df=mdy-all}}</ref> macOS also used to support the [[Java Platform]] as a "preferred software package"—in practice this means that applications written in Java fit as neatly into the operating system as possible while still being [[cross-platform]] compatible, and that graphical user interfaces written in [[Swing (Java)|Swing]] look almost exactly like native Cocoa interfaces. Since 2014, Apple has promoted its new programming language [[Swift (programming language)|Swift]] as the preferred language for software development on Apple platforms.

Apple's original plan with macOS was to require all developers to rewrite their software into the Cocoa APIs. This caused much outcry among existing Mac developers, who threatened to abandon the platform rather than invest in a costly rewrite, and the idea was shelved.<ref name="Rhapsody and Blues"/><ref name="Photoshop, Lightroom, and Adobe's 64-bit roadmap"/> To permit a smooth transition from Mac OS 9 to Mac OS X, the [[Carbon (API)|Carbon]] [[Application Programming Interface]] (API) was created.<ref name="Rhapsody and Blues"/> Applications written with Carbon were initially able to run natively on both classic Mac OS and Mac OS X, although this ability was later dropped as Mac OS X developed. Carbon was not included in the first product sold as Mac OS X: the little-used original release of [[Mac OS X Server 1.0]], which also did not include the Aqua interface.<ref>{{Cite news |title=Looking back at OS X's origins |work=Macworld |url=https://www.macworld.com/article/1154036/osxorigins.html |access-date=September 25, 2020 |archive-date=January 3, 2012 |archive-url=https://web.archive.org/web/20120103080604/http://www.macworld.com/article/154036/2010/09/osxorigins.html |url-status=live}}</ref> Apple limited further development of Carbon from the release of Leopard onwards and announced that Carbon applications would not run at 64-bit.<ref name="Photoshop, Lightroom, and Adobe's 64-bit roadmap">{{Cite web |last=Nack |first=John |title=Photoshop, Lightroom, and Adobe's 64-bit roadmap |url=https://blogs.adobe.com/jnack/2008/04/photoshop_lightroom_and_adobes_64-bit_road.html |url-status=live |archive-url=https://web.archive.org/web/20150414030843/https://blogs.adobe.com/jnack/2008/04/photoshop_lightroom_and_adobes_64-bit_road.html |archive-date=April 14, 2015 |access-date=March 30, 2016 |publisher=[[Adobe Systems]] |df=mdy-all}}</ref><ref name="Rhapsody and Blues"/> A number of macOS applications continued to use Carbon for some time afterwards, especially ones with heritage dating back to the classic Mac OS and for which updates would be difficult, uneconomic or not necessary. This included [[Microsoft Office]] up to [[Microsoft Office 2016|Office 2016]], and Photoshop up to CS5.<ref name="Office 2016 preview 9to5 Mac">{{Cite web |last=Hall |first=Zac |date=March 5, 2015 |title=Back to the Mac: Microsoft releases redesigned Office for Mac 2016 Preview w/ Retina support, collaboration, more |url=https://9to5mac.com/2015/03/05/microsoft-office-mac-2016-preview |url-status=live |archive-url=https://web.archive.org/web/20171228000253/https://9to5mac.com/2015/03/05/microsoft-office-mac-2016-preview |archive-date=December 28, 2017 |access-date=27 December 2017 |website=9to5 Mac |df=mdy-all}}</ref><ref name="Photoshop, Lightroom, and Adobe's 64-bit roadmap"/> Early versions of macOS could also run some classic Mac OS applications through the [[Classic Environment]] with performance limitations; this feature was removed from 10.5 onwards and all Macs using Intel processors.

Because macOS is [[POSIX]] compliant, many software packages written for the other [[Unix-like]] systems including [[Linux]] can be recompiled to run on it, including many scientific and technical programs.<ref name="Mainzer">{{Cite web |last=Steele |first=Billy |title=NASA WISE Deputy Project Scientist Amy Mainzer |url=https://www.engadget.com/2013/05/24/engadget-questionnaire-nasa-amy-mainzer |url-status=live |archive-url=https://web.archive.org/web/20170625164201/https://www.engadget.com/2013/05/24/engadget-questionnaire-nasa-amy-mainzer |archive-date=June 25, 2017 |website=Engadget |date=May 24, 2013 |quote=As an astrophysicist, having the Unix core underlying the OS is key, since virtually all of our software is Unix-based in some sense |df=mdy-all}}</ref> Third-party projects such as [[Homebrew (package management software)|Homebrew]], [[Fink (software)|Fink]], [[MacPorts]] and [[pkgsrc]] provide pre-compiled or pre-formatted packages. Apple and others have provided versions of the [[X Window System]] graphical interface which can allow these applications to run with an approximation of the macOS look-and-feel.<ref>{{Cite web |date=October 28, 2003 |title=X11 for Mac OS X 1.0 |url=https://support.apple.com/downloads/X11_for_Mac_OS_X_1_0 |url-status=live |archive-url=https://web.archive.org/web/20081224160753/https://support.apple.com/downloads/X11_for_Mac_OS_X_1_0 |archive-date=December 24, 2008 |access-date=December 15, 2008 |publisher=[[Apple Inc.|Apple]] |df=mdy-all}}</ref><ref>{{Cite web |last=Ben Byer |date=October 27, 2007 |title=Re: X11 in Leopard: xterm on start-up |url=https://lists.apple.com/archives/x11-users/2007/Oct/msg00065.html |url-status=live |archive-url=https://web.archive.org/web/20080210000444/https://lists.apple.com/archives/X11-users/2007/Oct/msg00065.html |archive-date=February 10, 2008 |access-date=January 18, 2008 |website=Apple's x11-users mailing list |df=mdy-all}}</ref><ref>{{Cite web |last=Michael Larabel |date=May 28, 2011 |title=X.Org Server 1.10.2 Brings A Bunch Of Bug-Fixes |url=https://www.phoronix.com/scan.php?page=news_item&px=OTQ5OA |url-status=live |archive-url=https://web.archive.org/web/20110603150322/https://www.phoronix.com/scan.php?page=news_item&px=OTQ5OA |archive-date=June 3, 2011 |access-date=May 29, 2011 |publisher=phoronix |df=mdy-all}}</ref> The current Apple-endorsed method is the open-source [[XQuartz]] project; earlier versions could use the [[X11.app|X11]] application provided by Apple, or before that the [[XDarwin]] project.<ref>{{Cite web |last=Slivka |first=Eric |date=February 17, 2012 |title=Apple Removes X11 in OS X Mountain Lion, Shifts Support to Open Source XQuartz |url=https://www.macrumors.com/2012/02/17/apple-removes-x11-in-os-x-mountain-lion-shifts-support-to-open-source-xquartz |url-status=live |archive-url=https://web.archive.org/web/20120222214936/https://www.macrumors.com/2012/02/17/apple-removes-x11-in-os-x-mountain-lion-shifts-support-to-open-source-xquartz |archive-date=February 22, 2012 |access-date=February 23, 2012 |website=MacRumors |df=mdy-all}}</ref>

Applications can be distributed to Macs and installed by the user from any source and by any method such as downloading (with or without [[code signing]], available via an Apple developer account) or through the [[Mac App Store]], a marketplace of software maintained by Apple through a process requiring the company's approval. Apps installed through the Mac App Store run within a [[Sandbox (computer security)|sandbox]], restricting their ability to exchange information with other applications or modify the core operating system and its features. This has been cited as an advantage, by allowing users to install apps with confidence that they should not be able to damage their system, but also as a disadvantage due to blocking the Mac App Store's use for professional applications that require elevated privileges.<ref name="Not on the Mac App Store">{{Cite web |last=Counsell |first=Dan |date=November 16, 2015 |title=Not on the Mac App Store |url=https://dancounsell.typed.com/articles/not-on-the-mac-app-store |archive-url=https://web.archive.org/web/20151208082109/https://dancounsell.typed.com/articles/not-on-the-mac-app-store |archive-date=December 8, 2015}}</ref><ref name="Distributing Apps Outside the Mac App Store">{{Cite web |title=Distributing Apps Outside the Mac App Store |url=https://developer.apple.com/library/mac/documentation/IDEs/Conceptual/AppDistributionGuide/DistributingApplicationsOutside/DistributingApplicationsOutside.html |url-status=live |archive-url=https://web.archive.org/web/20151208143842/https://developer.apple.com/library/mac/documentation/IDEs/Conceptual/AppDistributionGuide/DistributingApplicationsOutside/DistributingApplicationsOutside.html |archive-date=December 8, 2015 |access-date=1 December 2015 |website=Apple Developer |publisher=Apple |df=mdy-all}}</ref> Applications without any code signature cannot be run by default except from a computer's administrator account.<ref name="How to open apps from an unidentified developer in OS X Mountain Lion">{{Cite web |last=Kazmucha |first=Allyson |date=October 4, 2019 |title=How to open apps from an unidentified developer in OS X Mountain Lion |url=https://www.imore.com/how-open-apps-anywhere-macos-catalina-and-mojave |access-date=September 25, 2020 |website=IMore |archive-date=December 31, 2021 |archive-url=https://web.archive.org/web/20211231130043/https://www.imore.com/how-open-apps-anywhere-macos-catalina-and-mojave |url-status=live}}</ref><ref name="About Gatekeeper">{{Cite web |title=About Gatekeeper |url=https://support.apple.com/en-us/HT202491 |url-status=live |archive-url=https://web.archive.org/web/20151204142544/https://support.apple.com/en-us/HT202491 |archive-date=December 4, 2015 |access-date=1 December 2015 |publisher=Apple |df=mdy-all}}</ref>

Apple produces macOS applications. Some are included with macOS and some sold separately. This includes [[iWork]], [[Final Cut Pro]], [[Logic Pro]], [[iLife]], and the database application [[FileMaker]]. Numerous other developers also offer [[List of Macintosh software|software for macOS]].

In 2018, Apple introduced an application layer, codenamed Marzipan, to [[Porting|port]] iOS apps to macOS.<ref name="Gurman Marzipan rumor">{{Cite news |last=Gurman |first=Masrk |date=December 20, 2017 |title=Apple Plans Combined iPhone, iPad & Mac Apps to Create One User Experience |work=Bloomberg.com |url=https://www.bloomberg.com/news/articles/2017-12-20/apple-is-said-to-have-plan-to-combine-iphone-ipad-and-mac-apps |access-date=2 February 2019 |archive-date=November 23, 2021 |archive-url=https://web.archive.org/web/20211123171922/https://www.bloomberg.com/news/articles/2017-12-20/apple-is-said-to-have-plan-to-combine-iphone-ipad-and-mac-apps |url-status=live}}</ref><ref name="Steinberger Marzipan">{{Cite web |last=Steinberger |first=Peter |title=Marzipan: Porting iOS Apps to the Mac |url=https://pspdfkit.com/blog/2018/porting-ios-apps-to-mac-marzipan-iosmac-uikit-appkit |access-date=2 February 2019 |publisher=PSPDFKit |archive-date=August 26, 2022 |archive-url=https://web.archive.org/web/20220826231543/https://pspdfkit.com/blog/2018/porting-ios-apps-to-mac-marzipan-iosmac-uikit-appkit/ |url-status=live}}</ref> macOS Mojave included ports of four first-party iOS apps including [[HomeKit|Home]] and [[Apple News|News]], and it was announced that the API would be available for third-party developers to use from 2019.<ref name="Verge future of the Mac comes from iOS">{{Cite web |last1=Gartenberg |first1=Chaim |last2=Bohn |first2=Dieter |date=June 7, 2018 |title=The future of the Mac comes from iOS apps |url=https://www.theverge.com/2018/6/7/17438450/apple-marzipan-mac-ios-apps-port-mojave-appkit-uikit-future-platform-software |access-date=29 January 2019 |website=The Verge |archive-date=November 11, 2021 |archive-url=https://web.archive.org/web/20211111003424/https://www.theverge.com/2018/6/7/17438450/apple-marzipan-mac-ios-apps-port-mojave-appkit-uikit-future-platform-software |url-status=live}}</ref><ref name="iMore Marzipan">{{Cite web |last=Ritchie |first=Rene |date=June 4, 2018 |title=Marzipan: What you need to know about iOS apps on the Mac |url=https://www.imore.com/marzipan |access-date=29 January 2019 |website=iMore |archive-date=August 18, 2021 |archive-url=https://web.archive.org/web/20210818144750/https://www.imore.com/marzipan |url-status=live}}</ref><ref name="Marzipan Benjamin Mayo">{{Cite web |last=Mayo |first=Benjamin |title=Marzipan |url=https://benjaminmayo.co.uk/marzipan |access-date=29 January 2019 |website=benjaminmayo.co.uk |date=September 25, 2018 |archive-date=April 14, 2019 |archive-url=https://web.archive.org/web/20190414093038/http://benjaminmayo.co.uk/marzipan |url-status=live}}</ref> With [[macOS Catalina]] in 2019, the application layer was made available to third-party developers as [[Mac Catalyst]].<ref>{{Cite web |title=Mac Catalyst |url=https://developer.apple.com/mac-catalyst/ |access-date=2022-10-06 |website=Apple Developer |language=en |archive-date=September 22, 2022 |archive-url=https://web.archive.org/web/20220922025050/https://developer.apple.com/mac-catalyst/ |url-status=live}}</ref>