Exporting the same image into three different sizes for your iPhone application is a really troublesome process, and this post aims to solve this problem by showing you how to use a single vector in Xcode 6.4.
Export the vector file into PDF format from Sketch.
Go to your Assets.xcassets in Xcode and add new image set.
Select the image
Go to inspector tab
Change scale factors to
Drag and drop the exported PDF file into the Universal slot.