Instagram浏览器无法处理ICS链接

Question

我有一个指向ICS日历的链接：See here

除Instagram应用内浏览器外，每个浏览器都可以正确处理它（在桌面上下载文件并在iPhone上打开日历应用）-当您在Instagram中打开此链接（如来自Direct Messages）时，它仅显示文件内容。

如何强制Instagram应用打开此类链接的日历应用？

这是我用来生成此文件的PHP代码的一部分：

    $calendar_string = [];
    $calendar_string[] = "BEGIN:VCALENDAR\n";
    $calendar_string[] = "VERSION:2.0\n";
    $calendar_string[] = "PRODID:-//Veronika Agafonova//NONSGML Veronika Agafonova//EN\n";
    $calendar_string[] = "METHOD:REQUEST\n"; // requied by Outlook
    $calendar_string[] = "BEGIN:VEVENT\n";
    $calendar_string[] = "UID:".date('Ymd').'T'.date('His')."-".rand()."-example.com\n"; // required by Outlok
    $calendar_string[] = "DTSTAMP:".date('Ymd').'T'.date('His')."\n"; // required by Outlook
    $calendar_string[] = "DTSTART:$date_start\n";
    $calendar_string[] = "DTEND:$date_end\n";
    $calendar_string[] = "SUMMARY:$title\n";
    $calendar_string[] = "DESCRIPTION:$details\n";
    $calendar_string[] = "END:VEVENT\n";
    $calendar_string[] = "END:VCALENDAR\n";

    header("Content-Type: text/Calendar");
    header("Content-Disposition: attachment; filename=calendar.ics");
    header("Content-Length: ". strlen(implode("", $calendar_string)).";");
    header("Content-Type: application/force-download");
    header("Content-Transfer-Encoding: binary");
    header("Connection: close");

    echo implode("", $calendar_string);