match-then-free.php

<?php
public function match( $match, $operator, $value ) {

	$value = $this->get_value( $value );

	if ( '==' == $operator ) :
		// Promotion: If cart match the category and greater than two then shipping free
		$count = 0;
		foreach ( WC()->cart->get_cart() as $product ) :

			if ( has_term( $value, 'product_cat', $product['product_id'] )) :
				$count = $count + $product['quantity'];
				return ($count >= 2) ? true : false;
			endif;

		endforeach;
		// Backup: If any item in cart matched the category then shipping free
		// foreach ( WC()->cart->get_cart() as $product ) :

		// 	if ( has_term( $value, 'product_cat', $product['product_id'] ) ) :

		// 		return true;
		// 	endif;

		// endforeach;

	elseif ( '!=' == $operator ) :

		$match = true;
		foreach ( WC()->cart->get_cart() as $product ) :

			if ( has_term( $value, 'product_cat', $product['product_id'] ) ) :
				return false;
			endif;

		endforeach;

	endif;

	return $match;

}