I love that my macOS computer unlocks when I sit down. This little piece of magic is due to my Watch. It has to be on your wrist and unlocked. You also must enable the ability in macOS System Preference (step 5-6 below) to work. Your watch, iPhone, and Mac must be on the same network.
Sometimes, after it’s been working for a while, it may just stop. Usually because something has changed. In my case, it was a new iPhone (actually replacement due to failure) that caused mine to stop working. Here is how I fixed it. These steps were provided by Apple Support and augmented with my own experience.
- System Preferences > iCloud > uncheck Keychain
- Keychain Access > Preferences > Reset My Default Keychains
- Reboot Mac
- You’ll be asked to enter your iCloud password – enter it. If not, then go into iCloud setting and recheck Keychain. You may be prompted to enter multiple passwords. Follow the prompts. Once it stays checked, then give iCloud a few minutes to sync up.
- System Preferences > Security & Privacy > Click the lock to make changes (ensure it’s UNLOCKED – if it already is, skip this step)
- Check Allow your Apple Watch to unlock your Mac
- Enable Back to Mac. (This is not needed for Mojave.)
I also find that my Phone must be reasonably close by. All of this magic depends on bluetooth and wifi. If your phone is misreporting your location, it may not work.