My app has been supporting at least iOS6 using Xcode5.1 storyboard.

After I did several work in Xcode 6 GM, I need to test on iOS 6 Simulator.
 Xcode 6 GM does not have iOS 6 Simulator.So, I opened my project in Xcode 5.1.

But It fails to build. I cannot even open the storyboard in Xcode5.1.

At the navigation pane, it says 

```
Main_iPhone.storboard
Interface Builder Storyboard Compiler Error
The document"(null)" requires Xcode6.0 or later.

```

And when I click it, a prompt appears 

```
The document "Main_iPhone.storyboard" requires Xcode 6.0 or later.
This version does not support constraints to layout margins. Open this document with Xcode 6.0 or later.

```