Disclaimer: Brand new to iOS dev. Go easy on me.
Got a funny situation in Xcode 4.5. My Size Inspector looks like this:
In Xcode 4.5, for iOS 6 and OSX 10.8 development, AutoLayout is being enabled by default.
To turn it off, open your xib file and click on a blank spot (not on a view or any component). On the inspector panel, select the first tab and remove the "Use Autolayout" checkbox. Your springs and struts will be back.