Script to lock your Mac via the screensaver when you unplug your iPhone

lockwatcher.py

#!/usr/bin/env python

import subprocess
import threading
import time


class Scanner():
    def __init__(self):
        self.stop = threading.Event()
        self.iphone_present = None

    def start(self):
        while not self.stop.is_set():
            self.scan()
            time.sleep(1)

    def scan(self):
        output = subprocess.check_output(['/usr/sbin/ioreg'])
        if 'iPhone' in output:
            self.iphone_present = True
        else:
            if self.iphone_present:
                self.lock()
            self.iphone_present = False

    def lock(self):
        subprocess.call([
            'open', '-a',
            '/System/Library/Frameworks/ScreenSaver.framework/Versions/A/Resources/ScreenSaverEngine.app'
        ])

    def quit(self):
        self.stop.set()


try:
    scanner = Scanner()
    scanner.start()
except KeyboardInterrupt:
    scanner.quit()