I know I can open the settings app in iOS 5 using
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@\"prefs://\"]];
but is
Using the prefs:root scheme is not recommended. It will very likely be a breaking change with iOS update on the device and could lead to your app being rejected from the app store.
prefs:root
https://gist.github.com/phynet/471089a51b8f940f0fb4