Welcome to Swift!

Swift is a high performance systems programming language. It has a clean and modern syntax, and offers seamless access to existing C and Objective-C code and frameworks, and is memory safe (by default).

Although inspired by Objective-C and many other languages, Swift is not itself a C-derived language. As a complete and independent language, Swift packages core features like flow control, data structures, and functions, with high-level constructs like objects, protocols, closures, and generics. Swift embraces modules, eliminating the need for headers and the code duplication they entail.

Documentation

To read the documentation, start by installing the Sphinx documentation generator tool (sphinx-doc.org, just run easy_install -U Sphinx from the command line and you’re good to go). Once you have that, you can build the swift documentation by going into swift/docs and typing make. This compiles the ‘rst’ files in the docs directory into HTML in the swift/docs/_build/html directory.

Once built, the best place to start is with the swift whitepaper, which gives a tour of the language (in swift/docs/_build/html/whitepaper/index.html). Another potentially useful document is docs/LangRef, which gives a low level tour of how the language works from the implementation perspective.

Many of the docs are out of date, but you can see some historical design documents in the docs directory.

Another source of documentation is the standard library itself, located at swift/stdlib. Much of the language is actually implemented in the library (including Int), and the standard library gives some examples of what can be expressed today.

Getting Started

These instructions give the most direct path to a working Swift development environment. Options for doing things differently are discussed below.

System Requirements

OS X, Ubuntu Linux LTS, and the latest Ubuntu Linux release are the current supported host development operating systems.

For OS X, you need the latest Xcode.

For Ubuntu, you’ll need the following development dependencies:

sudo apt-get install git cmake ninja-build clang uuid-dev libicu-dev icu-devtools libbsd-dev libedit-dev libxml2-dev libsqlite3-dev swig libpython-dev libncurses5-dev pkg-config
Copy the code

Note: LLDB currently requires at least swig-1.3.40 but will successfully build with version 2 shipped with Ubuntu.

If you are building on Ubuntu 14.04 LTS, you’ll need to upgrade your clang compiler for C++14 support and create a symlink:

Sudo apt-get install clang-3.6 sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-3.6 100 sudo Update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-3.6 100Copy the code

Getting Sources for Swift and Related Projects

 git clone [email protected]:/apple/swift.git swift
 git clone [email protected]:/apple/swift-llvm.git llvm
 git clone [email protected]:/apple/swift-clang.git clang
 git clone [email protected]:/apple/swift-lldb.git lldb
 git clone [email protected]:/apple/swift-cmark.git cmark
 git clone [email protected]:/apple/swift-llbuild.git llbuild
 git clone [email protected]:/apple/swift-package-manager.git swiftpm
 git clone [email protected]:/apple/swift-corelibs-xctest.git 
 git clone [email protected]:/apple/swift-corelibs-foundation.git 
Copy the code

CMake is the core infrastructure used to configure builds of Swift and its companion projects; at least version 2.8.12.2 is required. Your favorite Linux distribution likely already has a CMake package you can install. On OS X, you can download the CMake Binary Distribution, bundled as an application, copy it to /Applications, and add the embedded command line tools to your PATH:

export PATH=/Applications/CMake.app/Contents/bin:$PATH
Copy the code

Ninja is the current recommended build system for building Swift and is the default configuration generated by CMake. If you’re on OS X or don’t install it as part of your Linux distribution, clone it next to the other projects and it will be bootstrapped automatically:

git clone [email protected]:martine/ninja.git
Copy the code

You can also use a third-party packaging tool like Homebrew to install CMake and Ninja on OS X:

brew install cmake ninja
Copy the code

Building Swift

The build-script is a high-level build automation script that supports basic options such as building a Swift-compatible LLDB, building the Swift Package Manager, building for iOS, running tests after builds, and more. It also supports presets which you can define for common combinations of build options.

To find out more:

swift/utils/build-script -h
Copy the code

Note: Arguments after “–” above are forwarded to build-script-impl, which is the ultimate shell script that invokes the actual build and test commands.

A basic command to build Swift and run basic tests with Ninja:

swift/utils/build-script -t
Copy the code

Develop Swift in Xcode

The Xcode IDE can be used to edit the Swift source code, but it is not currently fully supported as a build environment for SDKs other than OS X. If you’d like to build for other SDKs but still use Xcode, once you’ve built Swift using Ninja or one of the other supported CMake generators, you can set up an IDE-only Xcode environment using the build-script’s -X flag:

swift/utils/build-script -X --skip-build -- --reconfigure
Copy the code

The --skip-build flag tells build-script to only generate the project, not build it in its entirety. A bare minimum of LLVM tools will build in order to configure the Xcode projects.

The --reconfigure flag tells build-script-impl to run the CMake configuration step even if there is a cached configuration. As you develop in Xcode, you may need to rerun this from time to time to refresh your generated Xcode project, picking up new targets, file removals, or file additions.

Testing Swift

See docs/Testing.rst.

Contributing to Swift

Contributions to Swift are welcomed and encouraged! Please see the Contributing to Swift guide.