This project will introduce you to three important iOS technologies together: Touch ID, Face ID and the keychain. The first two are used to identify users biometrically using the fingerprint sensor on iPhones and iPads, or the face scanner on iPhone X; the latter is a secure, encrypted data storage area on every device that you can read and write to.
Of course, there's little point learning about technologies without using them, so this project will have you build a secure text editor. Users can type whatever they want and have it saved, but to read it again they'll need to unlock the app using Touch ID or Face ID.
You might remember in project 12 that I said
UserDefaults is great for its simplicity but isn't good for private data. Well, the keychain is securely encrypted, so we can be assured that data we put there is safe.
Make a new Single View App project in Xcode named Project28. Note: I recommend you run this project on a real device, because there are reports that the simulator doesn’t work well with the keychain right now.