Determine if user navigated from mobile Safari

Question

I have an app, and I'd like to redirect the users to different pages based on where they are navigating from.

If navigating from web clip, do not redirect. If navigating from mobile Safari, redirect to safari.aspx. If navigating from anywhere else, redirect to unavailable.aspx

I was able to use iPhone WebApps, is there a way to detect how it was loaded? Home Screen vs Safari? to determine if the user was navigating from a web clip, but I'm having trouble determining if the user navigated from mobile Safari on an iPhone or iPod.

Here's what I have:

if (window.navigator.standalone) {
    // user navigated from web clip, don't redirect
}
else if (/*logic for mobile Safari*/) {
    //user navigated from mobile Safari, redirect to safari page
    window.location = "safari.aspx";
}
else {
    //user navigated from some other browser, redirect to unavailable page
    window.location = "unavailable.aspx";
}

Answer 1

See https://developer.chrome.com/multidevice/user-agent#chrome_for_ios_user_agent - the user agent strings for Safari on iOS and for Chrome on iOS are inconveniently similar:

Chrome

Mozilla/5.0 (iPhone; U; CPU iPhone OS 5_1_1 like Mac OS X; en) AppleWebKit/534.46.0 (KHTML, like Gecko) CriOS/19.0.1084.60 Mobile/9B206 Safari/7534.48.3

Safari

Mozilla/5.0 (iPhone; U; CPU like Mac OS X; en) AppleWebKit/420+ (KHTML, like Gecko) Version/3.0 Mobile/1A543 Safari/419.3

Looks like the best approach here is to first of all check for iOS as other answers have suggested and then filter on the stuff that makes the Safari UA unique, which I would suggest is best accomplished with "is AppleWebKit and is not CriOS":

var ua = window.navigator.userAgent;
var iOS = !!ua.match(/iPad/i) || !!ua.match(/iPhone/i);
var webkit = !!ua.match(/WebKit/i);
var iOSSafari = iOS && webkit && !ua.match(/CriOS/i);