XCode

Xcode is an integrated development environment for macOS containing a suite of software development tools developed byApple for developing software for macOS, iOS, watchOS and tvOS. First released in 2003, the latest stable release is version 9.0 and is available via the Mac App Store free of charge for macOS Sierra users.[2] Registered developers can downloadpreview releases and prior versions of the suite through the Apple Developer website

Xcode supports source code for the programming languages C, C++, Objective-C, Objective-C++, Java, AppleScript, Python, Ruby, ResEdit (Rez), and Swift, with a variety of programming models, including but not limited to Cocoa, Carbon, and Java. Third parties have added support for GNU Pascal,[4] Free Pascal,[5] Ada,[6] C#,[7] Perl,[8] and D. Thanks to the Mach-O executable format, which allows fat binary files, containing code for multiple architectures, Xcode can build universal binary files, which allow software to run on both PowerPC and Intel-based (x86) platforms and that can include both 32-bit and 64-bit code for both architectures. Using the iOS SDK, Xcode can also be used to compile and debug applications for iOS that run on ARM architecture processors. Xcode includes the GUI tool Instruments, which runs atop a dynamic tracing framework, DTrace, created by Sun Microsystems and released as part of OpenSolaris. The main application of the suite is the integrated development environment (IDE), also named Xcode. The Xcode suite includes most of Apple's developer documentation, and built-in Interface Builder, an application used to construct graphical user interfaces. Up to Xcode 4.1, the Xcode suite included a modified version of the GNU Compiler Collection. In Xcode 3.1 up to Xcode 4.6.3, it included the LLVM-GCC compiler, with front ends from the GNU Compiler Collection and a code generator based on LLVM.[9] In Xcode 3.2 and later, it included the Clang C/C++/Objective-C compiler, with newly-written front ends and a code generator based on LLVM, and the Clang static analyzer.[10] Starting with Xcode 4.2, the Clang compiler became the default compiler,[11] Starting with Xcode 5.0, Clang was the only compiler provided. Up to Xcode 4.6.3, the Xcode suite used the GNU Debugger (GDB) as the back-end for the IDE's debugger. Starting with Xcode 4.3, the LLDB debugger was also provided; starting with Xcode 4.5 LLDB replaced GDB as the default back-end for the IDE's debugger.[12] Starting with Xcode 5.0, GDB was no longer supplied Formerly, Xcode supported distributing a product build process over multiple systems. One technology involved was named Shared Workgroup Build, which used the Bonjour protocol to automatically discover systems providing compiler services, and a modified version of the free software product distcc to facilitate the distribution of workloads. Earlier versions of Xcode provided a system named Dedicated Network Builds. These features are absent in the supported versions of Xcode. Xcode also includes Apple's WebObjects tools and frameworks for building Java web applications and web services (formerly sold as a separate product). As of Xcode 3.0, Apple dropped[14] WebObjects development inside Xcode; WOLips[15] should be used instead. Xcode 3 still includes the WebObjects frameworks.

Xcode 1.0 was released in fall 2003. Xcode 1.0 was based on Project Builder, but had an updated user interface (UI), ZeroLink, Fix & Continue, distributed build support, and Code Sense indexing. The next significant release, Xcode 1.5, had better code completion and an improved debugger. Xcode 2.0 was released with Mac OS X v10.4 "Tiger". It included the Quartz Composer visual programming language, better Code Sense indexing for Java, and Ant support. It also included the Apple Reference Library tool, which allows searching and reading online documentation from Apple’s website and documentation installed on a local computer. Xcode 2.1 could create universal binary files. It supported shared precompiled headers, unit testing targets, conditional breakpoints, and watchpoints. It also had better dependency analysis. The final version of Xcode for Mac OS X v10.4 was 2.5. Xcode 3.0 was released with Mac OS X v10.5 "Leopard". Notable changes since 2.1 include[16] the DTrace debugging tool (now named Instruments), refactoring support, context-sensitive documentation, and Objective-C 2.0 with garbage collection. It also supports Project Snapshots, which provide a basic form of version control; Message Bubbles, which show build errors debug values alongside code; and building four-architecture fat binaries (32 and 64-bit Intel and PowerPC). Xcode 3.1 was an update release of the developer tools for Mac OS X, and was the same version included with the iPhone SDK. It could target non-Mac OS X platforms, including iPhone OS 2.0. It included the GCC 4.2 and LLVM GCC 4.2 compilers. Another new feature since Xcode 3.0 is that Xcode's SCM support now includes Subversion 1.5. Xcode 3.2 was released with Mac OS X v10.6 "Snow Leopard" and installs on no earlier version of OS X. It supports static program analysis, among other features. It also drops official support for targeting versions earlier than iPhone OS 3.0. But it is still possible to target older versions, and the simulator supports iPhone OS 2.0 through 3.1. Also, Javasupport is "exiled" in 3.2 to the organizer.[17] Xcode 3.2.6 is the last version that can be downloaded for free for users of Mac OS X v10.6. Downloading it requires a free registration at Apple's developer site. In June 2010, at the Apple Worldwide Developers Conference version 4 of Xcode was announced during the Developer Tools State of the Union address. Version 4 of the developer tools consolidates the Xcode editing tools and Interface Builder into one application, among other enhancements.[18][19] Apple released the final version of Xcode 4.0 on March 9, 2011. The software was made available for free to all registered members of the $99 per year Mac Developer program and the $99 per year iOS Developer program. It was also sold for $4.99 to non-members on the Mac App Store (no longer available). Xcode 4.0 drops support for many older systems, including all PowerPC development andsoftware development kits (SDKs) for Mac OS X 10.4 and 10.5, and all iOS SDKs older than 4.3. The deployment target can still be set to produce binaries for those older platforms, but for Mac OS platforms, one is then limited to creating x86 and x86-64 binaries. Later, Xcode was free to the general public. Before version 4.1, Xcode cost $4.99.[20] Xcode 4.1 was made available for free on July 20, 2011 (the day of Mac OS X Lion's release) to all users of Mac OS X Lion on the Mac App Store. On August 29, 2011, Xcode 4.1 was made available for Mac OS X Snow Leopard for members of the paid Mac or iOS developer programs.[21] Xcode 4.1 was the last version to include GNU Compiler Collection(GCC) instead of only LLVM GCC or Clang. On October 12, 2011, Xcode 4.2 was released concurrently with the release of iOS 5.0, and it included many more and improved features, such as storyboarding and automatic reference counting (ARC).[11] Xcode 4.2 is the last version to support Mac OS X 10.6 "Snow Leopard", but is only available to registered developers with paid accounts; without a paid account, 3.2.6 is the latest download that appears for Snow Leopard.  

Xcode 4.3, released on February 16, 2012, is distributed as one application bundle, Xcode.app, installed from the Mac App Store. Xcode 4.3 reorganizes the Xcode menu to include development tools.[23] Xcode 4.3.1 was released on March 7, 2012 to add support for iOS 5.1.[24] Xcode 4.3.2 was released on March 22, 2012 with enhancements to the iOS Simulator and a suggested move to the LLDB debugger versus the GDB debugger (which appear to be undocumented changes).[citation needed] Xcode 4.3.3, released in May 2012, featured an updated SDK for Mac OS X 10.7.4 "Lion" and a few bug fixes. Xcode 4.4 was released on July 25, 2012.[26] It runs on both Mac OS X Lion (10.7) and OS X Mountain Lion (10.8) and is the first version of Xcode to contain the OS X 10.8 "Mountain Lion" SDK. Xcode 4.4 includes support for automatic synthesizing of declared properties, new Objective-C features such as literal syntax and subscripting, improved localization, and more.[27] On August 7, 2012, Xcode 4.4.1 was released with a few bug fixes. On September 19, 2012, iOS 6 and Xcode 4.5 were released. Xcode added support for iOS 6 and the 4-inch Retina Display on iPhone 5 and iPod touch 5th generation. It also brought some new Objective-C features to iOS, simplified localization, and added auto-layout support for iOS.[12] On October 3, 2012, Xcode 4.5.1 was released with bug fixes and stability improvements.[2] Less than a month later, Xcode 4.5.2 was released, with support for iPad Mini and iPad with Retina Display, and bug fixes and stability improvements. On January 28, 2013, iOS 6.1 and Xcode 4.6 were released. In June 2013, at the Apple Worldwide Developers Conference, version 5 of Xcode was announced.[28] On September 18, 2013 Xcode 5.0 was released. It added support for iOS 7 SDK, with always support of OS X 10.8 Mountain Lion SDK but not the support of OS X 10.9 Mavericks SDK. This latest was only included in the betas version. It also added a version of Clang generating 64-bit ARM code for iOS 7. Apple removed support for building garbage collected Cocoa binaries in Xcode 5.1. On June 2, 2014 at the World Wide Developers Conference, Apple announced version 6 of Xcode. Features include Playgrounds, live debugging tools, and a new programming language named Swift.[30] On September 17, 2014, at the same time, iOS and Xcode 6 were released. Xcode could be downloaded on the Mac App Store.

On June 8, 2015 at the Apple Worldwide Developers Conference Xcode version 7 was announced. It introduced support for Swift 2, and Metal for OS X, and added support for deploying on iOS devices without an Apple Developer license.[31] Xcode 7 was released on September 16, 2015. On June 13, 2016 at the Apple Worldwide Developers Conference Xcode version 8 was announced. It introduced support for Swift 3.[32] Xcode 8 was released on September 13, 2016. On June 5, 2017 at the Apple Worldwide Developers Conference Xcode version 9 was announced. It introduced support for Swift 4 and Metal 2. It also introduced remotely debugging iOS and tvOS devices wirelessly through WiFi. Xcode 9 was publicly released on September 19, 2017.