Detecting iPhone/iPod/iPad clients on Google App engine

Recently, while working on a fun little side project (www.coolchars.com), we needed to detect and render a very different page for iPhone users (no Flash and slightly different page structure to accommodate iPhone copy&paste)


When the iPhone (or iPod/iPad) requests a url, it includes a user-agent string like the following:

Mozilla/5.0 (iPhone; U; CPU like Mac OS X; en) AppleWebKit/420+ (KHTML, like Gecko) Version/3.0 Mobile/1A543a Safari/419.3

To detect and parse that from a webapp-based application on appengine, just do the following:

import os
from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app
from google.appengine.ext.webapp import template

class MainPage(webapp.RequestHandler):
 def get(self):
     user_agent = self.request.headers.get('User-Agent', '').lower()
     iphone = 'iphone' in user_agent or 'ipod' in user_agent

     if iphone:
         self.redirect('/index_iphone.html')
     else:
         self.redirect('/index.html')

application = webapp.WSGIApplication([('/', MainPage)], debug=True)

def main():
 run_wsgi_app(application)

if __name__ == "__main__":
 main()

Of course you can do something more sophisticated like parsing and rendering templates differently, but this is just an example.

A quick way to test it out is launch Safari, go to Develop->User Agent->Other, and pop-in the user-agent string at the top of this blog entry. Be sure to test it out on the simulator or the actual device since screen size will affect rendering as well.