I'm using Sketch to create images that will be used in my Xcode 6 auto-layout storyboards. However I can not get the image sizes correct. They always appear too large and overflow the storyboard view controller. Is there a way in Xcode to see the dimensions the storyboard expects? Is there a systematic way to do this...rather than trial and error?
Storyboard, especially in auto layout mode, doesn't expect any dimensions – dimensions will depend on device screen (in reality) or on simulated metrics (in Interface Builder in Xcode).
What matters is aspect ratio and presence of three resource files (three sizes – regular, 2x and 3x).
You can see the list of dimensions here: http://www.paintcodeapp.com/news/iphone-6-screens-demystified
So, let's say you want to insert an image that occupies the whole width of the screen, and the height is chosen automatically so that to keep the aspect ratio. What you could do:
Moreover, you can see current width and height of the simulated screen in Metrics tab. But those will change every time you change your preview (simulated) device type.