Merge pull request #302 from jcesarmobile/add-permission-check

iOS: Added camera permission ckeck and fail if it's not permitted

Closes #301

src/ios/CDVBarcodeScanner.mm

@@ -138,6 +138,15 @@ - (NSString*)isScanNotPossible {
     return result;
 }
 
+-(BOOL)notHasPermission
+{
+    AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
+    return (authStatus == AVAuthorizationStatusDenied ||
+            authStatus == AVAuthorizationStatusRestricted);
+}
+
+
+
 //--------------------------------------------------------------------------
 - (void)scan:(CDVInvokedUrlCommand*)command {
     CDVbcsProcessor* processor;
@@ -160,6 +169,10 @@ - (void)scan:(CDVInvokedUrlCommand*)command {
     if (capabilityError) {
         [self returnError:capabilityError callback:callback];
         return;
+    } else if ([self notHasPermission]) {
+        NSString * error = NSLocalizedString(@"Access to the camera has been prohibited; please enable it in the Settings app to continue.",nil);
+        [self returnError:error callback:callback];
+        return;
     }
 
     processor = [[CDVbcsProcessor alloc]