Updated 19/05/2011
There’s not a lot of information surrounding the new persistent wifi feature in iOS 4 and how it affects iPhones. I did some experimentation and managed to find something which i’d like to share with those who are seeking the same information.
First of all on iPod Touches, persistent wifi works as advertised and stays on wether or not the phone is plugged into the charger. This is so it can maintain a constant data connection for Push Notifications and mail checking.
Now for iPhones. Prior to iOS 4.3, persistent wifi worked albeit conditionally and under the following conditions:
- 3G is unavailable
- Cellular data is turned off
- iPhone is plugged into charger
But post 4.3, persistent wifi will ONLY work under the following condition:
- iPhone is plugged into charger
This situation may or may not change in the future but I will update this post when I have more info.