Use the latest LAPolicy for iOS9+ which allows a fallback to using the device pin code

Author: ddaddy

LTHPasscodeViewController/LTHPasscodeViewController.m

@@ -353,8 +353,13 @@ - (void)_setupFingerPrint {
     if (!self.biometricsContext && _allowUnlockWithBiometrics && !_useFallbackPasscode) {
         self.biometricsContext = [[LAContext alloc] init];
 
+        LAPolicy policy = LAPolicyDeviceOwnerAuthenticationWithBiometrics;
+        if (@available(iOS 9.0, *)) {
+            policy = LAPolicyDeviceOwnerAuthentication;
+        }
+        
         NSError *error = nil;
-        if ([self.biometricsContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {
+        if ([self.biometricsContext canEvaluatePolicy:policy error:&error]) {
             if (error) {
                 return;
             }
@@ -370,7 +375,7 @@ - (void)_setupFingerPrint {
             _animatingView.hidden = YES;
 
             // Authenticate User
-            [self.biometricsContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
+            [self.biometricsContext evaluatePolicy:policy
                                 localizedReason:LTHPasscodeViewControllerStrings(self.biometricsDetailsString)
                                           reply:^(BOOL success, NSError *error) {