Can't see Preview Assistant in my xcode 6, xcode 7 beta
Open the storyboard or xib file in the Builder interface.
Select View> Assistant Editor> Show Assistant Editor.
The helper editor opens the implementation file corresponding to the storyboard or xib file.
Open the Assistant pop-up menu.
The Assistant pop-up menu is the first item to the right of the back and forth arrows in the editor assistant navigation bar.
From the pop-up menu, go to Preview and select a storyboard file or xib.
The layout preview appears in the editor assistant. (For Mac apps, if the preview is not displayed, select either icon or outline view.)
Select preview options.
To view the layout in a different localization, choose a language from the pop-up menu in the lower-right corner of the preview.
To preview a mock iOS app for different devices in different versions of iOS, click the Add button in the lower-left corner of the preview and select a device from the pop-up menu.
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