// add function in FUNCTIONS.php
if ( is_page( 'Download' )

    } else {
    require_once( get_template_directory() . '/mobile_detect/Mobile_Detect.php');

global $detect;
if ( class_exists( 'Mobile_Detect' ) ):
        $detect = new Mobile_Detect;
endif;

if( $detect->isiOS() ) {wp_redirect( 'https://itunes.apple.com/au/app/stashd/id714814803?mt=8'); exit(0); };
    }
}