How to unlock the app using Touch ID and Face ID in Swift.

Easiest way to implement Touch ID and Face ID for your app.

Touch ID and Face ID

Touch ID and Face ID let users to access the app, in a much easier way. To access the Touch ID and Face ID, we need to import LocalAuthentication framework.

Let’s see the implementation of Touch Id and Face ID :-

1. Import the LocalAuthentication framework and create an instance of LAContext.

Creating an instance of LAContext

LAContext :- A mechanism for evaluating authentication policies and access controls.

2. Check whether the device is capable of supporting biomertic authentication and is confirgured by users in the app settings by calling the method canEvaluatePolicy(_:error:).

Checking device capability for biometric

The policy controls how the authentication behaves. For example, the LAPolicy.deviceOwnerAuthentication policy used in this sample indicates that reverting to a passcode is allowed when biometrics fails or is unavailable. Alternatively, you can indicate the LAPolicy.deviceOwnerAuthenticationWithBiometrics policy, which doesn’t allow reverting to the device passcode.

3. If the device is capable , then the system biometric check will begin — explaining the reason why the system is asking for authentication.

For Touch ID, the reason is written in code and for Face ID its mentioned in info.plist.

System biometric check

4. After the successful authentication, unlock the app.

Flow Chart for better understanding.

FlowChart

Now let see the code:-

HandlePressMe() will handle the code for biometric authentication. This function will be called on the click of Press Me button.

Function for biometric Authentication

Demo

Demo for LocalAuthentication

Here is the sample code in Github repository.

Reference link :-

Apple Doc :- Logging a User into Your App with Face ID or Touch ID
Touch to activate: Touch ID, Face ID and LocalAuthentication

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