function isIos() {
  return isIphone() || isIpad() || isIpod();
}
Returns whether the platform is iOS.
Note that iPadOS 13+ spoofs macOS Safari by default in its user agent, and in
this scenario the platform will not be recognized as iOS. If you must have
iPad-specific behavior, use
{@link goog.labs.userAgent.extra.isSafariDesktopOnMobile}.
@return {boolean} Whether the platform is iOS.