How Apple Watch Password Lock Works

apple-watch-password-lock-mechanism.md

addObserver(IPHONE_DID_UNLOCKED) {
  if isOnSkin {
    locked = false
  }
}

addObserver(WATCH_OFF_SKIN) {
  locked = true
}

func watchOn() {
  if isLocked {
    requirePasswdToUnlock()
  }
  ...
}

func watchOff() {
  if isOffSkin {
    locked = true
  }
  ...
}

Whenever you take off Apple Watch, it gets locked.

Apple Watch stays unlocked only after you put on it, and unlock it or unlock paired iPhone once.