Use pdfs as texture source in Xcode 6 sprite level editor

In iOS applications, we can now use pdf files, and at the compilation stage, the corresponding dimensional .pngs are created (including the dimensional and named files @ 2x and @ 3x). Can the same format be used to generate textures of the correct size for use in a sprite set?

The spritekit level editor "sees" the images in the files in the preview area in the lower right corner of the editor, but unlike standard .pngs that can be simply dragged into the level editor, PDF files will not work.