Apple made the iPhone the center of your digital life, turning into a sort of media, email, health, and security hub. An Apple Watch is an even further distillation of truly personal technology. Apple relies on proximity and other cues to let a Watch, iPhone, and Mac unlock each other without requiring additional authentication.
You can unlock from one device to another in the following combinations.
Unlock your iPhone with Face ID using an Apple Watch
Apple added a feature in iOS 14.5 and watchOS 7.4 to help with the problem of masks obscuring faces for correct Face ID recognition. In Settings > Face ID & Passcode, you can enable Unlock with Apple Watch. This only works with iPhones that have Face ID and you have Face ID active.
To use your Watch to unlock your iPhone, you must have a passcode set for your Watch and wrist detection enabled; your Watch must then be on your wrist and unlocked. (Use the Watch app’s Passcode settings to add a passcode and turn on Wrist Detection.) Wi-Fi and Bluetooth must be enabled on both devices, too. Your Watch and iPhone must be within about 10 meters (33 feet), the standard distance cited for Bluetooth, but range may vary–closer will work more reliably than farther away.
Even further, your iPhone must fail at unlocking via Face ID because of face coverings as identified by iOS. Then, and only then, your iPhone will unlock via authentication from your Watch. When it works, you’ll get a couple of vibrations via haptic feedback on your Watch, and a banner will briefly appear on your iPhone. A Lock button appears momentarily on your Watch, too, which you can tap if you unlocked your iPhone by accident. If you tap Lock, you have to use your passcode to unlock your iPhone the next time you do so.
While it seems like many conditions, I’ve seen it work consistently even when Face ID with a Mask is also enabled in Settings > Face ID & Passcode on my iPhone and Face ID fails to recognize me right away.
Unlock your Apple Watch from an iPhone
Conversely, you can use your iPhone to unlock your Watch. In the Watch app, go to Passcode and enable Unlock with iPhone. If just put your Watch on your wrist or it’s locked for another reason, unlocking your iPhone in proximity will also unlock your Watch. Your iPhone briefly shows a banner with a Lock button you can tap to cancel the operation. If you don’t tap it, your Watch is unlocked.
This feature appeared early on with the Watch–so early that Apple didn’t document when it was first available. You can use it with any working Watch and iPhone paired with it.
Unlock a Mac from an Apple Watch
In 2016, Apple updated macOS to let you unlock your computer via a Watch in proximity. It works with any Watch model and most models of Macs running macOS versions released since late 2016. Your Watch and the Mac must be logged in to the same Apple ID, and two-factor authentication must be enabled on the Apple ID account. (Apple sherlockedKnock, an app that could use an iPhone or Watch to unlock your Mac.)
Go to System Preferences > Security & Privacy > General and check “Use your Apple Watch to unlock apps and your Mac.” Enter your administrative password. macOS then communicates with your Watch, which must be unlocked and on your wrist, and enables the feature.
In the upcoming macOS 13 Ventura, you might be prompted to turn the unlock feature on, as I was after enabling it on a different Mac on my network that was still running macOS 12 Monterey. To enable it, go to System Settings > Touch ID & Password and enable the feature under Apple Watch.
The next time your Mac is locked, merely being in proximity while wearing your Watch will unlock macOS. The usual disclaimers apply: it only works to unlock not login. You have to enter your Mac account’s password after a restart, starting up from being powered off, or logging in if you’ve logged out but not powered down.
This feature also lets you use your Watch instead of entering an administrative password or using Touch ID on equipped Macs or with the Magic Keyboard with Touch ID with M-series Apple silicon Macs. Your Watch will use haptics for attention and then prompt you to double-click the side button to approve.
As a security precaution, Apple doesn’t let you unlock your Mac if its screen is being shared.
Apple advises that you can check to see if this feature will work on your Mac: hold down Option and choose > System Information and click Wi-Fi. Auto Unlock appears as a line item, and the app will show Supported if it works on your Mac.
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