 <p>You can stretch an image while preserving the aspect ratio of a portion of that image using slicing. Xcode offers a graphical interface for doing this. The idea is that you decide what parts of the image are allowed to stretch and which aren't.</p> <p><a href="https://developer.apple.com/library/ios/recipes/xcode_help-image_catalog-1.0/chapters/SlicinganImage.html" rel="nofollow">https://developer.apple.com/library/ios/recipes/xcode_help-image_catalog-1.0/chapters/SlicinganImage.html</a></p>