Like others here, I was apprehensive about buying this based on the reviews… but I read reviews that said.. “follow the instructions and you’ll have no problems”… and they were right. I have a 2012 Mac Mini, iPhone 6+, and Watch Sport, all running the latest software versions available as of this writing. It works PERFECTLY. Yes.. you have to wake your Mac up first if it’s asleep.. press a key, wiggle the mouse, smack the magic trackpad, whatever. Then I literally pick my phone up and knock on it twice like I’m knocking on a door.. without even waking the phone up. BUT- when I leave my phone in the other room and I’m wearing my Watch, I can just raise my wrist, swipe up to reveal the Knock Glance, tap, and it unlocks my Mac! It even shows the status of my Mac.. locked or unlocked. It may sound like a lot but it’s honestly twice as fast as typing in my password each time. AND I can LOCK my Mac while I’m ‘Netflix-ing and Chilling’ in the living room. Highly recommended. Excellent app.
Bryen about Knock – unlock your Mac without a password using your iPhone and Apple Watch