Source

File: wp-includes/functions.php

function _device_can_upload() {
	if ( ! wp_is_mobile() ) {
		return true;
	}

	$ua = $_SERVER['HTTP_USER_AGENT'];

	if ( strpos( $ua, 'iPhone' ) !== false
		|| strpos( $ua, 'iPad' ) !== false
		|| strpos( $ua, 'iPod' ) !== false ) {
			return preg_match( '#OS ([\d_]+) like Mac OS X#', $ua, $version ) && version_compare( $version[1], '6', '>=' );
	}

	return true;
}