Mailchimp integration connection admin notice example.

woocommerce-api-connection-admin-notice-example.php

// Display an admin notice, if setup is required.
add_action( 'admin_notices', array( $this, 'maybe_display_admin_notices' ) );

/**
 * Display an admin notice, if not on the integration screen and if the account isn't yet connected.
 * @access public
 * @since  1.0.0
 * @return void
 */
public function maybe_display_admin_notices () {
	if ( isset( $_GET['page'] ) && 'wc-settings' == $_GET['page'] && isset( $_GET['section'] ) && 'mailchimp' == $_GET['section'] ) return; // Don't show these notices on our admin screen.

	// Find a different method of retrieving this value.
	$api_key = WC()->integrations->integrations['mailchimp']->get_option( 'wc_mailchimp_api_key' );

	if ( '' == $api_key ) {
		$url = $this->get_settings_url();
		echo '<div class="updated fade"><p>' . sprintf( __( '%sWooCommerce MailChimp is almost ready.%s To get started, %sconnect your MailChimp account%s.', 'woocommerce-mailchimp-integration' ), '<strong>', '</strong>', '<a href="' . esc_url( $url ) . '">', '</a>' ) . '</p></div>' . "\n";
	}
} // End maybe_display_admin_notices()

/**
 * Generate a URL to our specific settings screen.
 * @access public
 * @since  1.0.0
 * @return string Generated URL.
 */
public function get_settings_url () {
	$url = admin_url( 'admin.php' );
	$url = add_query_arg( 'page', 'wc-settings', $url );
	$url = add_query_arg( 'tab', 'integration', $url );
	$url = add_query_arg( 'section', 'mailchimp', $url );

	return $url;
}