I’ve been working on an asyncio eventloop for PyObjC on and of over the last couple of months. This has finally resulted in an initial release (1.0b1) on PyPI: objc_asyncio.

The code is complete, with proper test coverage, but I haven’t seriously used the library yet which is why I’ve started out with a beta release. For now the library requires Python 3.8 or 3.9, support for 3.7 is on my roadmap.

To use asyncio in a Cocoa GUI:

import sys
import Cocoa

import objc_asyncio

with objc_asyncio.running_loop():
    Cocoa.NSApplicationMain(sys.argv)

The, fairly minimal, documentation is found at read the docs, although the regular asyncio documentation and resources should be used to learn how to use asyncio.

Installation:

$ python3.8 -m pip install --pre objc_asyncio

This has taken more time than I’d expected up front, it didn’t help that I basically didn’t know asyncio before I started.

I’m not entirely happy with the amount of code in the library, I had to clone a lot of standard library code because the builtin loops assume that Python is in control of the eventloop itself and because I try to avoid depending on private APIs. Luckily it was possible to keep a clear separation between my own code and code cloned from asyncio.

I’ve started work on an asyncio event loop for PyObjC. This currently can basically just run the script below, but should improve soon enough…

from objc_asyncio import _loop as loop

el = loop.EventLoop()
el.call_soon(lambda a: print(a), "hello world")
el.call_later(1.0, lambda: print("timer 1"))
el.call_later(2.0, lambda: print("timer 2"))
el.call_later(2.5, lambda: el.stop())
el.run_forever()