Xcode Storyboard preview size classes blank

问题

I have a problem with storyboard preview. When I select a old ViewController created with a previous version of Xcode (6.0), the preview show me only the navigation bar. But, if I create a new ViewController and put inside it some elements, the preview works. The current version of Xcode is the 6.3.2.

Thanks

回答1:

The interface elements that you put inside the "old ViewController" were added under a particular size class. You are not in that size class with your preview, so those interface elements are not present.

来源：https://stackoverflow.com/questions/31119771/xcode-storyboard-preview-size-classes-blank