Methods of iPad Detection in Web Applications

With all this Dashcode and iPhone web development exploration that I’ve been doing lately, the question of course came up in my mind… what about the iPad? I’m already using some rudimentary sniffing to make sure iPhone users go to the appropriate spot, but obviously this case would have to be dealt with too, since maybe I would not want to send iPad users to the same spot as the iPhone users.

So I was very glad to find this article: iPad web development tips by Nicholas C. Zakas at his site, NCZOnline.

As it turns out, my method would have failed in that case since I have only been checking for “iPhone” (NOTE: strings are split on multiple lines to fit on this page… they actually don’t have line breaks.):

User-agent string

The previously-linked post describes the iPad Safari user-agent to be in the following format:

Mozilla/5.0 (iPad; U; CPU OS 3_2 like Mac OS X; en-us) 
AppleWebKit/531.21.10 (KHTML, like Gecko) 
Version/4.0.4 Mobile/7B334b Safari/531.21.10

This was the user-agent string during the beta testing phase. The format is slightly different for the final release: Although this appears to be the official user-agent string, I have received reports of a user-agent like this:

Mozilla/5.0(iPad; U; CPU iPhone OS 3_2 like Mac OS X; en-us) 
AppleWebKit/531.21.10 (KHTML, like Gecko) 
Version/4.0.4 Mobile/7B314 Safari/531.21.10

You’ll note the addition of “iPhone” in the operating system segment of the user-agent string. This brings the user-agent string for Safari on the iPad more into line with Safari on the iPhone and iPod Touch, which have the following user-agent strings, respectively:

Mozilla/5.0 (iPod; U; CPU iPhone OS 3_0 like Mac OS X; en-us) 
AppleWebKit/528.18 (KHTML, like Gecko) 
Version/4.0 Mobile/7A341 Safari/528.16

Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_0 like Mac OS X; en-us) 
AppleWebKit/528.18 (KHTML, like Gecko) 
Version/4.0 Mobile/7A341 Safari/528.16

This means a single user-agent string sniff for “iPhone” returns true in all three cases. The problem, of course, is that you might want to serve different experiences to the iPhone/iPod Touch than you would for the iPad. Make sure you double-check any user-agent sniffing designed to target these devices.

Then we move on to the interesting tidbit for the client-side. If detection is necessary, evidently we can use the navigator.platform property:

JavaScript iPad detection

If you’re trying to detect the iPad using JavaScript, there’s a very simple way to do so: check navigator.platform. The value of navigator.platform is always “iPad” when Safari for iPad is the user-agent. This follows the tradition of “iPhone” for the iPhone and “iPod” for the iPod Touch. This is the most accurate way to detect the iPad from JavaScript, assuming you don’t want to do a full user-agent string sniff.

function isIPad() {
    return navigator.platform == "iPad";
}

Also, keep in mind that navigator.platform doesn’t change even when the user-agent string for a browser is changed.

Good information for both sides of the computing fence, so I’m glad to have it!

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