In content-product.php I changed
if (is_out_of_stock()) {
echo '<span class="out-of-stock-badge">' . __( 'Sold', 'swiftframework' ) . '</span>';
} else if ($product->is_on_sale()) {
echo apply_filters('woocommerce_sale_flash', '<span class="onsale">'. __( 'Sale!', 'swiftframework' ).'</span>', $post, $product);
} else if (!$product->get_price()) {
echo '<span class="free-badge">' . __( 'NFS', 'swiftframework' ) . '</span>';
and then in product-image.php I have changed to
if (is_out_of_stock()) {
echo '<span class="out-of-stock-badge">' . __( 'Sold', 'swiftframework' ) . '</span>';
} else if ($product->is_on_sale()) {
echo apply_filters('woocommerce_sale_flash', '<span class="onsale">'.__( 'Sale!', 'swiftframework' ).'</span>', $post, $product);
} else if (!$product->get_price()) {
echo '<span class="free-badge">' . __( 'NFS', 'swiftframework' ) . '</span>';