Over the weekend one of my colleagues (thanks Neil!) reported that a mobile site we developed was not working properly for him although strangely was functioning fine on his girlfriends phone.
I was unable to recreate the issue on various i-devices I had so I wondered if it was some caching issue so got the user to clear his cache.
What it turned out to be however was that after upgrading to IOS 5 Safari’s cookie settings get changed to never accept cookies (sometimes!). This is obviously going to stop a lot of sites from working properly (including anything that uses session as this is maintained through a cookie).
I can’t find any official release notes/bug report detailing this but have found countless posts indicating that this occurs e.g.:
You dont have a lot of choice really but to add a bit of script that attempts to set a cookie and warn the user if it cant that cookies have been disabled and provide some instructions about how to re-enable them.
ASP.net sites could look at enabling cookie-less sessions.
In IOS5 cookies can be enabled by going to Settings, Safari, Accept Cookies and change to Always.