TouchID : How to get touch id authentication attempts? - ios

Question

I need to implement touch ID and have to show alert to user for authentication attempts left. Below code Im using.
reply block not getting called after one wrong authentication attempt. Its getting called after 3 continues wrong authentication attempt. Is there any way to get count of wrong authentication attempts..?
LAContext *myContext = [[LAContext alloc] init];
NSError *authError = nil;
NSString *myLocalizedReasonString = #"Touch ID Test to show Touch ID working in a custom app";
if ([myContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&authError]) {
[myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
localizedReason:myLocalizedReasonString
reply:^(BOOL success, NSError *error) {
if (success) {
dispatch_async(dispatch_get_main_queue(), ^{
[self performSegueWithIdentifier:#"Success" sender:nil];
});
} else {
dispatch_async(dispatch_get_main_queue(), ^{
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"Error"
message:error.description
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil, nil];
[alertView show];
NSLog(#"Switch to fall back authentication - ie, display a keypad or password entry box");
});
}
}];
} else {
dispatch_async(dispatch_get_main_queue(), ^{
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"Error"
message:authError.description
delegate:self
cancelButtonTitle:#"OK"
otherButtonTitles:nil, nil];
[alertView show];
});
}

Answer 1

I went through the documentation, it is not possible to show alert in each failed attempt. Just refer the documentation
LocalAuthentication in iOS. You can show alerts at different error cases. After 3rd failed attempt LAError.authenticationFailed will be called and after 5th failed attempt LAError.touchIDLockout will be called. You can display the alerts here. For more info refer Apple LAError documentation.