Using Face ID and Touch ID, the iOS app can authorize your identity and send the log in information to the back-end without any user interaction with the app. This is one of the most secure way to identify the user. Let's see how to implement it.
Touch ID and Face ID demo. Many users rely on biometric authentication like Face ID or Touch ID to enable secure, effortless access to their devices. As a fallback option, and for devices without biometry, a passcode or password serves a similar purpose. Use the LocalAuthentication framework to leverage these mechanisms in your app and extend authentication procedures your app already implements.
Accessing Keychain Items with Face ID or Touch ID. When you store a secure item like a password or a private key in the keychain, you dictate the conditions under which that item can be accessed later. Among other things, you can tell keychain services that every time it tries to read the item, it should first seek the user’s permission—for example, by authenticating the user biometrically with Face ID or Touch ID. You rely on both the Security and LocalAuthentication frameworks to enable this behavior.