Xcode 4.1+ Autolayout checkbox missing

Question

I am trying to enable autolayout for an iOS project but cannot find the checkbox in the info panel. I know it's supposed to be under the versioning section and above Localization. I also see that the documentation says:

Note: Auto Layout is available only in Mac OS X v10.7 Lion and later. If you are running Xcode 4 in Mac OS X v10.6 Snow Leopard, Auto Layout is not available.

from: http://developer.apple.com/LIBRARY/IOS/#documentation/ToolsLanguages/Conceptual/Xcode4UserGuide/InterfaceBuilder/InterfaceBuilder.html

I'm on Lion and running Xcode 4.2 and the checkbox is not showing. Any thoughts?

Answer 1

Auto Layout is implemented in AppKit in 10.7, so 10.7 is required to develop and to run. It isn't in iOS 4 or 5.