Detect if device is iOS

Detecting iOS

With iOS 13 iPad both User agent and platform strings are changed and differentiating between iPad and MacOS seems possible, so all answers below needs to take that into account now.

This might be the shortest alternative that also covers iOS 13:

function iOS() {
  return [
    'iPad Simulator',
    'iPhone Simulator',
    'iPod Simulator',
    'iPad',
    'iPhone',
    'iPod'
  ].includes(navigator.platform)
  // iPad on iOS 13 detection
  || (navigator.userAgent.includes("Mac") && "ontouchend" in document)
}

iOS will be either true or false

Worse option: User agent sniffing

User Agent sniffing is more dangerous and problems appear often.

On iPad iOS 13, the user agent is identical with that of a MacOS 13 computer, but if you ignore iPads this might work still for a while:

var iOS = !window.MSStream && /iPad|iPhone|iPod/.test(navigator.userAgent); // fails on iPad iOS 13

The !window.MSStream is to not incorrectly detect IE11, see here and here.

Note: Both navigator.userAgent and navigator.platform can be faked by the user or a browser extension.

Browser extensions to change userAgent or platform exist because websites use too heavy-handed detection and often disable some features even if the user's browser would otherwise be able to use that feature.

To de-escalate this conflict with users it's recommended to detect specifically for each case the exact features that your website needs. Then when the user gets a browser with the needed feature it will already work without additional code changes.

Detecting iOS version

The most common way of detecting the iOS version is by parsing it from the User Agent string. But there is also feature detection inference*;

We know for a fact that history API was introduced in iOS4 - matchMedia API in iOS5 - webAudio API in iOS6 - WebSpeech API in iOS7 and so on.

Note: The following code is not reliable and will break if any of these HTML5 features is deprecated in a newer iOS version. You have been warned!

function iOSversion() {

  if (iOS) { // <-- Use the one here above
    if (window.indexedDB) { return 'iOS 8 and up'; }
    if (window.SpeechSynthesisUtterance) { return 'iOS 7'; }
    if (window.webkitAudioContext) { return 'iOS 6'; }
    if (window.matchMedia) { return 'iOS 5'; }
    if (window.history && 'pushState' in window.history) { return 'iOS 4'; }
    return 'iOS 3 or earlier';
  }

  return 'Not an iOS device';
}

After iOS 13 you should detect iOS devices like this, since iPad will not be detected as iOS devices by old ways (due to new "desktop" options, enabled by default):

let isIOS = /iPad|iPhone|iPod/.test(navigator.platform)
|| (navigator.platform === 'MacIntel' && navigator.maxTouchPoints > 1)

The first condition for iOS < 13 or iPhone or iPad with disabled Desktop mode, the second condition for iPadOS 13 in the default configuration, since it position itself like Macintosh Intel, but actually is the only Macintosh with multi-touch.

Rather a hack than a real solution, but work reliably for me

P.S. As being said earlier, you probably should add IE checkup

let isIOS = (/iPad|iPhone|iPod/.test(navigator.platform) ||
(navigator.platform === 'MacIntel' && navigator.maxTouchPoints > 1)) &&
!window.MSStream

This sets the variable _iOSDevice to true or false

_iOSDevice = !!navigator.platform.match(/iPhone|iPod|iPad/);