Xcode 4 keyboard shortcut to switch build target destination
There is, is called Destination>select next destination. Go in the prefs in xcode and then in the key bindings tab, search for that, it will show what key it is set at.
For me, is cmd+alt+ctrl+] and [ to switch. Is quite useful, saves a few seconds.
In Xcode 4.6, the shortcut is ctrl+option+cmd+[ and ctrl+option+cmd+]
You can user ctrl + cmd + [ or ctrl + cmd + ] to select scheme, or use ctrl + cmd + [alt] [ or ctrl + cmd + [alt] ] to select productOr you can just search in the preference panel of key bindings for more information