Swiftpack.co - Package - rhx/SwiftGtk


A Swift wrapper around gtk-3.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/

What is new?

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.

Notable changes

  • Parameters use idiomatic Swift names (e.g. camel case instead of snake case, splitting out of "for", "from", etc.)
  • Requires Swift 5.2 or later
  • Uses the namespace referenced in the gir file
  • Wrapper code is now @inlinable to enable the compiler to optimise away most of the wrappers
  • Parameters and return types use more idiomatic Swift (e.g. Ref wrappers instead of pointers, Int instead of gint, etc.)
  • 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
  • Parameters or return types for records/classes now use the corresponding, lightweight Swift Ref wrapper instead of the underlying pointer


Normally, you don't build this package directly (but for testing you can - see 'Building' below), but you embed it into your own project. To use SwiftGtk, you need to use the Swift Package Manager. After installing the prerequisites (see 'Prerequisites' below), add SwiftGtk as a dependency to your Package.swift file, e.g.:

// swift-tools-version:5.2

import PackageDescription

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

At this stage, the Swift Package manager does not (yet) know how to run external programs such as gir2swift. Therefore the easiest way to compile your project with SwiftGtk is to use build scripts that do this for you and pass the necessary flags to the Swift Package manager (see the following section).


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.

To build your project, you then simply run


from within your project folder. On macOS, you can also 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 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+ should work fine), 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 5.2.4 (swiftlang-1103.0.32.1 clang-1103.0.32.29)
Target: x86_64-apple-darwin19.4.0

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

$ swift --version
Swift version 5.2.5 (swift-5.2.5-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, and 2.64, and gdk/gtk 3.22, and 3.24. 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

If you prefer a newer version of gtk, you can also install it from the GNOME 3 Staging PPA (see https://launchpad.net/~gnome3-team/+archive/ubuntu/gnome3-staging), but be aware that this can be a bit dangerous (as this removes packages that can be vital, particularly if you use a GNOME-based desktop), so only do this if you know what you are doing:

sudo add-apt-repository ppa:gnome3-team/gnome3-staging
sudo apt update
sudo apt dist-upgrade
sudo apt install libgtk-3-dev gir1.2-gtksource-3.0 gobject-introspection libgirepository1.0-dev libxml2-dev

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


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


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


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. Unfortunately, at this stage jazzy only works on macOS (and crashes under Linux), so this will currently only work on a Mac.


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!

Old Swift toolchain or Xcode

If you get an error such as

$ ./build.sh 
error: unable to invoke subcommand: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-package (No such file or directory)

this probably means that your Swift toolchain is too old. 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


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