         
         // Off Image
         if offImage == nil {
-            let imageStr = NSBundle(forClass: DZCheckBox.self).pathForResource("SwitchBackground_off", ofType: "png");
+            let imageStr = NSBundle(forClass: DZCheckBox.self).pathForResource(defaultOffImageName, ofType: defaultImageType);
             self.offImageView.image = UIImage(data: NSData(contentsOfURL: NSURL(fileURLWithPath: imageStr!))!);
         }
         else {

        }
    }
    
    // MARK: - @IBInspectable properties
    @IBInspectable public var onImage: UIImage?;
    @IBInspectable public var offImage: UIImage?;

        
        // Thumb Image
        if thumbImage == nil {
            let imageStr = NSBundle(forClass: DZCheckBox.self).pathForResource(defaultThumbImageName, ofType: defaultImageType);
            self.thumbImageView.image = UIImage(data: NSData(contentsOfURL: NSURL(fileURLWithPath: imageStr!))!);
        }
        else {
