A Swift wrapper around gtk-3.x and gtk-4.x that is largely auto-generated from gobject-introspection. This project tries to make gtk more “swifty” than using the plain C language interface. For up to date (auto-generated) reference documentation, see https://rhx.github.io/SwiftGtk/

macOS 11 build macOS 10.15 build macOS gtk4 build Ubuntu 20.04 build Ubuntu 18.04 build

What is new?

Support for gtk 4 was added via the gtk4 branch.

Version 12 of gir2swift pulls in PR#10, addressing several issues:

  • Improvements to the Build experience and LSP rhx/SwiftGtk#34
  • Fix issues with LLDB rhx/SwiftGtk#39
  • Controversial: Implicitly marks all declarations named “priv” as if they had attribute private=1
  • Prevents all “Private” records from generating unless generated in their instance record
    • -a option generates all records
  • Introduces CI
  • For Class metadata types no longer generates class wrappers. Ref structs now contain static method which returnes the GType of the class and instance of the Class metatype wrapped in the Ref struct.
  • Adds final class GWeak where T could be any Ref struct of a type which supports ARC. This class is a property wrapper which contains weak reference to any instance of T. This is especially beneficial for capture lists.
  • Adds support for weak observation.
  • Constructors and factories of GObjectInitiallyUnowned classes now consume floating reference upon initialisation as advised by the GObject documentation

Partially implemented:

Other Notable changes

Version 11 introduces a new type system into gir2swift, to ensure it has a representation of the underlying types. This is necessary for Swift 5.3 onwards, which requires more stringent casts. As a consequence, accessors can accept and return idiomatic Swift rather than underlying types or pointers. This means that a lot of the changes will be source-breaking for code that was compiled against libraries built with earlier versions of gir2swift.


Requires Swift 5.2 or later (Swift 5.3 is required for the gtk4 branch)
  • Uses the namespace referenced in the gir file
  • Wrapper code is now @inlinable to enable the compiler to optimise away most of the wrappers
  • Functions that take or return records now are templated instead of using the type-erased Protocol
  • ErrorType has been renamed GLibError to ensure it neither clashes with Swift.Error nor the GLib.ErrorType scanner enum


Normally, you don’t build this package directly (but for testing you can - see ‘Building’ below). Instead you need to embed SwiftGtk into your own project using the Swift Package Manager. After installing the prerequisites (see ‘Prerequisites’ below), you can do this by creating a new, empty project folder and then running the projgen.sh script, e.g.:

mkdir MyProject
cd MyProject
curl -L https://git.io/SwiftGtk3.sh | sh

After this, you should be able to import Gtk in your sources and use swift build to build your project. Alternatively, you can manually download run-gir2swift.sh and add SwiftGtk as a dependency to your Package.swift file, e.g.:

// swift-tools-version:5.3

import PackageDescription

let package = Package(name: "MyPackage",
    dependencies: [
        .package(name: "gir2swift", url: "https://github.com/rhx/gir2swift.git", .branch("main")),
        .package(name: "Gtk", url: "https://github.com/rhx/SwiftGtk.git", .branch("gtk3")),
    targets: [.target(name: "MyPackage", dependencies: ["Gtk"])]

For gtk4 replace .branch("gtk3") with .branch("gtk4").


You can find some example projects on GitHub that show how to use SwiftGtk:

Build Scripts

The demo applications come with build scripts that configure some environment variables and pass required arguments when calling swift build, swift package, etc. The easiest way to get started is to clone one of the following projects, then copy all the *.sh shell scripts into your own project. Also, if you want to be able to build a desktop app, create a Resources folder, and copy (at least) the Info.plist file as well:

  • SwiftHelloGtk: this is a quick starting point for a simple gtk app that does not need any resources.
  • SwiftHelloGtkBuilder: this is a good starting point for a more complex app that has user interface files (*.ui) for GtkBuilder in its Resources folder.

You first need to create the Swift Wrappers using


After that, you can build, test, or run your project using the usual Swift compiler commands:

swift build
swift test
swift run

On macOS, there is an issue that requires you to pass in the required flags manually (see Building below). You can also build the project using Xcode on macOS instead. To do this, you need to create an Xcode project first, then open the project in the Xcode IDE:

open MyPackage.xcodeproj

After that, use the (usual) Build and Test buttons to build/test this package. Please note that, at this stage, the Swift Package manager is not able to create App targets for Xcode (so to build a macOs app rather than just a command line executable, you still need to use the build.sh script that calls app-wrapper.sh to create the standalone app bundle).



To build, you need at least Swift 5.2 (Swift 5.3 is required for gtk4; also some Linux distributions have issues and seem to require at least Swift 5.5), download from https://swift.org/download/ – if you are using macOS, make sure you have the command line tools installed as well). Test that your compiler works using swift --version, which should give you something like

$ swift --version
Apple Swift version 5.4 (swiftlang-1205.0.26.9 clang-1205.0.19.55)
Target: x86_64-apple-darwin20.5.0

on macOS, or on Linux you should get something like:

$ swift --version
Swift version 5.5 (swift-5.5-RELEASE)
Target: x86_64-unknown-linux-gnu

Gtk 3.22 or higher

The Swift wrappers have been tested with glib-2.56, 2.58, 2.60, 2.62, 2.64, 2.66, 2.68 and 2.70, and gdk/gtk 3.22, 3.24 as well as 4.0, 4.2 and 4.4 on the gtk4 branch. They should work with higher versions, but YMMV. Also make sure you have gobject-introspection and its .gir files installed.



On Ubuntu 20.04 and 18.04, you can use the gtk that comes with the distribution. Just install with the apt package manager:

sudo apt update
sudo apt install libgtk-3-dev gir1.2-gtksource-3.0 gobject-introspection libgirepository1.0-dev libxml2-dev jq

On Fedora 29, you can use the gtk that comes with the distribution. Just install with the dnf package manager:

sudo dnf install gtk3-devel pango-devel cairo-devel cairo-gobject-devel glib2-devel gobject-introspection-devel libxml2-devel jq


On macOS, you can install gtk using HomeBrew (for setup instructions, see http://brew.sh). Once you have a running HomeBrew installation, you can use it to install a native version of gtk:

brew update
brew install gtk+3 glib glib-networking gobject-introspection pkg-config jq


As pointed out in the ‘Usage’ section above, you don’t normally build this package directly, but instead you embed it into your own project. However, you can build and test this module separately to ensure that everything works. Make sure you have all the prerequisites installed (see above). After that, you can simply clone this repository and build the command line executable (be patient, this will download all the required dependencies and take a while to compile) using

git clone https://github.com/rhx/SwiftGtk.git
cd SwiftGtk
swift build
swift test

Please note that on macOS, due to a bug in the Swift Package Manager prior to Swift 5.4, if you have Xcode-12.4 or older, you need to pass in the build flags manually, i.e. instead of swift build and swift test you can run

swift build `./run-gir2swift.sh flags -noUpdate`
swift test  `./run-gir2swift.sh flags -noUpdate`


On macOS, you can build the project using Xcode instead. To do this, you need to create an Xcode project first, then open the project in the Xcode IDE:

open Gtk.xcodeproj

After that, use the (usual) Build and Test buttons to build/test this package.


You can find reference documentation inside the docs folder. This was generated using the jazzy tool. If you want to generate your own documentation, matching your local installation, you can use the generate-documentation.sh script in the repository. Make sure you have sourcekitten and jazzy installed, e.g. on macOS:

brew install sourcekitten
sudo gem install jazzy


Here are some common errors you might encounter and how to fix them.

SwiftGtk takes a very long time to build

Yes, gtk is a huge beast. The Swift interface generated from the gtk header files is close to 300,000 lines. This takes a long time to build!

Missing .gir Files

If you get an error such as

Girs located at
Cannot open '/GLib-2.0.gir': No such file or directory

Make sure that you have the relevant gobject-introspection packages installed (as per the Pre-requisites section), including their .gir and .pc files.

Old Swift toolchain or Xcode

If, when you run swift build, you get a Segmentation fault (core dumped) or circular dependency error such as

warning: circular dependency detected while parsing pangocairo: harfbuzz -> freetype2 -> harfbuzz

this probably means that your Swift toolchain is too old, particularly on Linux (at the time of this writing, some Linux distributions require at least Swift 5.5). Make sure the latest toolchain is the one that is found when you run the Swift compiler (see above).

If you get an older version, make sure that the right version of the swift compiler is found first in your PATH. On macOS, use xcode-select to select and install the latest version, e.g.:

sudo xcode-select -s /Applications/Xcode.app
xcode-select --install

Known Issues

  • When building, a lot of warnings appear. This is largely an issue with automatic RawRepresentable conformance in the Swift Standard library. As a workaround, you can turn this off by passing the -Xswiftc -suppress-warnings parameter when building.

  • The current build system does not support directory paths with spaces (e.g. the My Drive directory used by Google Drive File Stream).

  • BUILD_DIR is not supported in the current build system.

As a workaround, you can use the old build scripts, e.g. ./build.sh (instead of run-gir2swift.sh and swift build) to build a package.