1. Download the Mac app
Download MacID for Mac, as well as MacID for your iPhone (£2.99/$3.99/AU$5.99, App Store), which includes a Glance for Apple Watch.
Open the Mac app and choose 'Add iOS Device'. Both devices need Bluetooth turned on.
2. Pair the devices
Open the iOS app and the two devices should see each other. The Mac helper app will ask for your user account password and then store it securely.
Once paired, the app appears among the icons on the menu bar's right-hand side.
3. Lock from iPhone
In the iOS app, tap the Mac's name to lock the Mac's screen. Tap again to unlock it; this time you will need to place your finger on the Touch ID sensor to authorise the unlock.
You need to have set up Touch ID already for this to work.
