Category Dropdown Control

category-dropdown-control.php

/**
 * Make sure that custom controls are only defined in the Customizer
 */
if ( class_exists( 'WP_Customize_Control' ) ) :

	/**
	 * A custom category dropdown control for the Customizer
	 */
	class Theme_Slug_Category_Dropdown_Control extends WP_Customize_Control {
		/**
		 * Render Control
		 */
		public function render_content() {

			$categories = get_categories( array( 'hide_empty' => false ) );

			if ( ! empty( $categories ) ) : ?>

				<label>

					<span class="customize-control-title"><?php echo esc_html( $this->label ); ?></span>

					<select <?php $this->link(); ?>>

						<option value="0"><?php esc_html_e( 'All Categories', 'theme-slug' ); ?></option>

						<?php
						foreach ( $categories as $category ) :

							printf(	'<option value="%s" %s>%s</option>',
								absint( $category->term_id ),
								selected( $this->value(), $category->term_id, false ),
								esc_html( $category->name . ' (' . $category->count . ')' )
							);

						endforeach;
						?>

					</select>

				</label>

			<?php
			endif;

		}
	}
endif;

customizer.php

/**
 * Adds Featured Content section and category select setting.
 *
 * @param WP_Customize_Manager $wp_customize The Customizer object.
 */
function theme_slug_customize_register( $wp_customize ) {

	// Add featured content section.
	$wp_customize->add_section( 'theme_slug_featured_category', array(
		'title'    => esc_html__( 'Featured Content', 'theme-slug' ),
		'priority' => 120,
	) );

	// Add featured category setting and control.
	$wp_customize->add_setting( 'featured_category', array(
		'default'           => 0,
		'sanitize_callback' => 'absint',
		'transport'         => 'refresh',
	) );

	$wp_customize->add_control( new Theme_Slug_Category_Dropdown_Control( $wp_customize, 'featured_category', array(
		'label'       => esc_html__( 'Featured Category', 'theme-slug' ),
		'section'     => 'theme_slug_featured_category',
	) ) );

}
add_action( 'customize_register', 'theme_slug_customize_register' );