If you’re used to using Touch ID to unlock your iPhone, you might notice that iOS wants you to unlock using passcode whenever you restart your iPhone. Turns out that Touch ID can not replace the passcode completely. Taken from Apple’s iOS Security document, passcode is still required under the following circumstances:
- The device has just been turned on or restarted.
- The device has not been unlocked for more than 48 hours.
- The passcode has not been used to unlock the device in the last six days and TouchID has not unlocked the device in the last eight hours.
- The device has received a remote lock command.
- After five unsuccessful attempts to match a fingerprint.
- When setting up or enrolling new fingers with Touch ID.