PythonKit

Swift framework to interact with Python.

Requirements

PythonKit requires Swift 5 or higher and has been tested on macOS, Linux and Windows.

Usage

Some Python code like this:

import sys

print(f"Python {sys.version_info.major}.{sys.version_info.minor}")
print(f"Python Version: {sys.version}")
print(f"Python Encoding: {sys.getdefaultencoding().upper()}")

Can be implemented in Swift through PythonKit with the following code:

import PythonKit

let sys = try Python.import("sys")

print("Python \(sys.version_info.major).\(sys.version_info.minor)")
print("Python Version: \(sys.version)")
print("Python Encoding: \(sys.getdefaultencoding().upper())")

Swift Package Manager

Add the following dependency to your Package.swift manifest:

.package(url: "https://github.com/pvieito/PythonKit.git", .branch("master")),

Environment Variables

As the Python library are loaded at runtime by PythonKit, it will try to find the most modern Python version available in the system. You can force a given version with the PYTHON_VERSION environment variable or an specific Python library path or name with PYTHON_LIBRARY.

$ PYTHON_VERSION=3 swift run
[*] Python 3.5
$ PYTHON_VERSION=2.7 swift run
[*] Python 2.7
$ PYTHON_LIBRARY=libpython3.5.so swift run
[*] Python 3.5
$ PYTHON_LIBRARY=/usr/lib/x86_64-linux-gnu/libpython2.7.so swift run
[*] Python 2.7

If PythonKit cannot find and load the Python library you can set the PYTHON_LOADER_LOGGING environment variable to know from which locations PythonKit is trying to load the library:

$ PYTHON_LOADER_LOGGING=TRUE PYTHON_VERSION=3.8 swift run
Loading symbol 'Py_Initialize' from the Python library...
Trying to load library at 'Python.framework/Versions/3.8/Python'...
Trying to load library at '/usr/local/Frameworks/Python.framework/Versions/3.8/Python'...
Fatal error: Python library not found. Set the PYTHON_LIBRARY environment variable with the path to a Python library.

Notes

• Originally PythonKit was based on the Python module from the Swift for TensorFlow experimental project.
• If you have questions about PythonKit you can ask on the Swift Forums.