standalone_ios.md

Detect standalone IOS

// Detects if device is on iOS 
const isIos = () => {
  const userAgent = window.navigator.userAgent.toLowerCase();
  return /iphone|ipad|ipod/.test( userAgent );
}
// Detects if device is in standalone mode
const isInStandaloneMode = () => ('standalone' in window.navigator) && (window.navigator.standalone);

// Checks if should display install popup notification:
if (isIos() && !isInStandaloneMode()) {
  
    // "IOS : Not launched form the Home Screen";

}else if (isIos()){
  
   // "IOS : LAUNCHED form the Home Screen";
}

Can you detect iOS 13 with this?
Never tested it but from this StackOverflow answer it seems that you will need to use an additional check for iOS 13

const isIos13 = navigator.platform === 'MacIntel' && navigator.maxTouchPoints > 1;