Project28

Project 28. Secret Swift.

Concepts

• Touch ID, Face ID.
• Keychain.
• KeychainWrapper by Jason Rendel (MIT License) -> GitHub.
• resignFirstResponder()
• Local Authentication framework.
• LAContext, canEvaluatePolicy(), .deviceOwnerAuthenticationWithBiometrics

Notes

The Keychain is a secure, encrypted data storage area on every device that you can read and write to.

The resignFirstResponder() method is used to tell a view that has input focus that it should give up that focus. This is used to tell the text view that we're finished editing it, so the keyboard can be hidden.

TouchID, FaceID

Touch ID and Face ID are part of the Local Authentication framework. In this application the code does three things:

1. Check whether the device is capable of supporting biometric authentication.

2. If so, request that the biometry system begin a check now, giving it a string containing the reason why we're asking.

   • For TouchID, the string is written in code.
   • For FaceID, the string is written into the Info.plist file. You need to add a key called "Privacy - Face ID Usage Description"

3. If we get success back from the authentication request, it means this is the device's owner so we can unlock the app, otherwise, we show a failure message.

   • The success message might not be on the main thread, so we need to use async() to make sure we execure any user interface code on the main thread.