iOS Tutorial Use Face ID Touch ID and Passcode

This is a short tutorial/code snippet on how to successfully implement Touch ID in your app.
Thanks to @Semen Matusovskiy for his code.

You need this OBJC Code

#IF OBJC
#import <LocalAuthentication/LocalAuthentication.h>
- (void) authenticateButtonTapped
    {
   __result = -1; 
   LAContext *context = [[LAContext alloc] init];
   NSError *error = nil;
   if ([context canEvaluatePolicy: LAPolicyDeviceOwnerAuthentication error: &error])
       {
       [context evaluatePolicy: LAPolicyDeviceOwnerAuthentication localizedReason: @"Are you the device owner?" reply: ^(BOOL success, NSError *error)
           {
           if (error) { __result = 2; return; };
           if (success) { __result = 0; } else { __result = 1; };
           }
       ];
       }
    else
       { __result = 3; };
    }
#End If

Call it with this:

    Dim no As NativeObject = B4XPages.GetManager.GetTopPage.B4XPage 'if you dont use B4XPages then use "Me"
    no.RunMethod ("authenticateButtonTapped", Null)
    Do While result < 0
        Sleep (50)
    Loop
    Select Case result
        Case 0
            xui.MsgboxAsync ("Success: You are the device owner", "B4X")
        Case 1
            xui.MsgboxAsync ("Error: You are not the device owner", "B4X")
        Case 2
            xui.MsgboxAsync ("Error: There was a problem verifying your identity", "B4X")
        Case 3
            xui.MsgboxAsync ("Error: Your device cannot authenticate using TouchID", "B4X")
    End Select

This code asks for the Face ID, if this fails, then you have the choice to enter your pin code.

 

[Alexander Stolte]

If you only want FaceID with the option for your own Pincode then replace "LAPolicyDeviceOwnerAuthentication" with "LAPolicyDeviceOwnerAuthenticationWithBiometrics" then you can use your own pincode system.

also interesting:

LAPolicy.deviceOwnerAuthenticationWithBiometrics | Apple Developer Documentation

User authentication with biometry.

developer.apple.com

• LAPolicyDeviceOwnerAuthenticationWithWatch
  • User authentication with Apple Watch.
• LAPolicyDeviceOwnerAuthenticationWithBiometricsOrWatch
  • User authentication with either biometry or Apple Watch.
• LAPolicyDeviceOwnerAuthentication
  • User authentication with biometry, Apple Watch, or the device passcode.