You will need an installation of the Windows SDK to develop with the Swift Toolchain described here. An easy way to get the Windows SDK is to install Visual Studio, Visual Studio 2017 or later is needed. The following instructions suppose that you have Visual Studio installed. This will also make the x64 Native Tools Command Prompt ... available, it should be accessible from the Visual Studio ... folder in the Start menu.
Most of the following commands are to be executed from within this Native Tools Command Prompt. Be sure to always start the x64 version of the Native Tools Command Prompt.
You will need to copy a few files into the Windows SDK to make it usable for Swift development. (This is a one-time install, you do not need to update those files when you install newer versions of the Swift Toolchain.) As you might need administrator rights to copy files into the Visual Studio installation directory, for the following four commands (and for those commands only) open the Native Tools Command Prompt with administrator rights. Otherwise, you might get a "Permission denied" error for some of those commands. Be sure that all commands have been successfully executed before continuing.
To open the Native Tools Command Prompt with administrator rights, navigate to the according entry in the start menu, right-click on that entry and choose "Open location" in the context menu. Then right-click the according file (that is actually a link) and choose "Run as administrator".
Then execute the following four commands from within the Native Tools Command Prompt:
curl -L "https://raw.githubusercontent.com/apple/swift/master/stdlib/public/Platform/ucrt.modulemap" -o "%UniversalCRTSdkDir%\Include\%UCRTVersion%\ucrt\module.modulemap"
curl -L "https://raw.githubusercontent.com/apple/swift/master/stdlib/public/Platform/visualc.modulemap" -o "%VCToolsInstallDir%\include\module.modulemap"
curl -L "https://raw.githubusercontent.com/apple/swift/master/stdlib/public/Platform/visualc.apinotes" -o "%VCToolsInstallDir%\include\visualc.apinotes"
curl -L "https://raw.githubusercontent.com/apple/swift/master/stdlib/public/Platform/winsdk.modulemap" -o "%UniversalCRTSdkDir%\Include\%UCRTVersion%\um\module.modulemap"Close this instance of the Native Tools Command Prompt after those commands have been successfully executed.
The installation instructions that follow will result in a directory tree that has a well thought-out structure. To understand this directory structure better you may consult the details document.
- Go to https://dev.azure.com/compnerd/windows-swift.
- Choose
Pipelines>Pipelinesfrom the left of the dashboard. - Choose 'Runs'.
- Use the filter symbol to search for "VS2017".
- In the results list, scroll down until you see the first successful build (with a green OK symbol) that does not have "facebook" in the description and click on it.
- Under "Artifacts", click on the "... published" link.
- Download windows-toolchain-amd64.msi, windows-sdk.msi, and windows-runtime-amd64.msi by clicking on the appropriate down-arrows on the right. Be sure to really download these files from the same build (i.e. do not switch the build for the next download, and be careful when updating). These files will be downloaded as zip files. Unless they are not automatically unzipped during the download process, unzip them to obtain *.msi files in the extracted directories.
These *.msi files install the files to C:\Library. The complete Library directory can later be copied to a different location to be used there (but you have to change the PATH environment variable then).
To install the Swift Toolchain and Swift Windows SDK, run the installers windows-toolchain-amd64.msi and windows-sdk.msi. To install the Swift Runtime, run the installer windows-runtime-amd64.msi.
The installation of the Swift Toolchain adds the following value to the system PATH environment variable:
\Library\Developer\Toolchains\unknown-Asserts-development.xctoolchain\usr\bin
The installation of the Swift Runtime adds the following value to the system PATH environment variable:
\Library\Swift\Current\bin
On Windows, the most convenient setup for building Swift projects currently involves the use of CMake. This requires CMake 3.15+ for Swift support. You can download CMake from https://cmake.org.
You will need the ICU libraries from ICU - International Components for Unicode. The nightlies are built against ICU 64.2 from the ICU project. You can download the binaries for that via http://download.icu-project.org/files/icu4c/64.2/icu4c-64_2-Win64-MSVC2017.zip. In these instructions we assume you rename the extracted ICU folder icu4c-64_2-Win64-MSVC2017 to icu-64.2 and move it to C:\Library and that you rename bin64 to bin. The path to that bin should be added to the PATH environment variable.
You should use a CMake project to build a Swift program. An example CMake project with support for mixed-language support is available at https://github.com/compnerd/swift-cmake-demo, sample commands that build the project are documented there. The make commands are to be executed from the Native Tools Command Prompt. Note that the cmake executable to be used is the one mentioned above. (Try cmake -version to see which CMake version is actually being called.)
There is no need to call the compiled program from the Native Tools Command Prompt.
The addition of C:\Library\Swift\Current\bin to the PATH environment variable by the Swift Runtime installer ensures that the program can be run on the development machine. C:\Library\Swift\Current\bin contains the DLL files needed to run a Swift program (besides the fact that the DLL files from the ICU project icudt*.dll, icuin*.dll, icuio*.dll, icutu*.dll, and icuuc*.dll have to be in your path).
Of course, if you place the according DLL files from those directories into the same directory beside your executable (just copy them, do not move them!), you do not need the according additions to the PATH environment variable.
Note that the files in C:\Library\Swift\Current\bin might be incomplete: depending on the use case, you might need some more files (see the error messages when trying to run the program). You should find missing files in
C:\Library\Developer\Platforms\Windows.platform\Developer\SDKs\Windows.sdk\usr\bin
Copy the missing files to C:\Library\Swift\Current\bin (again, be sure not to move them). (But note that a new installation of the Swift Runtime does not update those copied files, so before installing a new Swift Runtime, first uninstall the old Swift Runtime and then delete all files in C:\Library\Swift\Current\bin.)
Tip: When calling your program from the command line, first execute the command chcp 65001 to ensure that Unicode characters are printed correctly inside the Windows command shell.
To run the Swift program on another machine, in addition to the files mentioned in the last section, the files from the "Visual C++ Redistributable" in the according version have to be available on that machine (i.e. they have to be in your path). They can be made available by installing the according "Visual C++ Redistributable". As an alternative, according to Distributable Code for Microsoft Visual Studio 2017 the files inside [VisualStudioFolder]\VC\redist are allowed to be part of your application (consider the files inside the subfolder x64\*.CRT). Please consult the Microsoft documentation to know which files you should bundle with your application.
You are responsible for any files that you distribute with your application. Read the license files for any files you want to distribute.