user_biometrics.md

Device Biometry with .NET MAUI

To use biometrics on your app, is going to need the Plugin.Fingerprint.
IMPORTANT: don't forget to click on Show Preleases and select the version 3.0.0 or above.

01. Setup:

On your MainActivity.cs file, add the following procedure:

protected override void OnCreate(Bundle savedInstanceState {
    base.OnCreate(savedInstanceState);
    CrossFingerprint.SetCurrentActivityResolver(() => this);
})

iOS:

Add this line into your info.plist.

<key>NSFaceIDUsageDescription</key>
    <string>MESSAGE</string>

Replace MESSAGE for another text - This is the text that appears for the user to approve the usage of Face/Touch ID.

Android:

To use on Android, add both options into your AndroidManifest.xml.
USER_FINGERPRINT is required for older Android versions and USER_BIOMETRIC is for the new ones.

<uses-permission android:name="android.permission.USE_BIOMETRIC" />
<uses-permission android:name="android.permission.USE_FINGERPRINT"/>

02. Code:

Before using any biometry on your program, first request if it's available to use:

var isBiometricAvailable = await CrossFingerprint.Current.IsAvailableAsync();
//// This won't ask the user if he would like to use biometry
// Just check if the device has an biometry and HAS registered at least one finger/face.

Now, let's scan user's face:

if (isBiometricAvailable){

    // This will ask user to give permission
    var authResult = await CrossFingerprint.Current.AuthenticateAsync("MESSAGE");

    if (authResult.Authenticated){
        // Biometry matches
    } else {
        // Biometry won't match
    }
}