I am able to export meshes created in Blender for use in SceneKit by using the COLLADA/.dae format - however no textures show up on iOS device.
Also, Preview on OS X
3 things I had to do to make it work.
Make sure images are packed in the .blend file (this is an option in UV editor)
when you export, the file will not automatically include the uv's or the materials. there is a checkbox to include the UV's and Materials in the DAE. I missed this as well when doing it.
This one you only need if your putting in a playground. The dae isn't quite applized, but i was able to use their scntool in the developer tools to export a dae that is. here is a sample command line that i used.
./scntool --convert ~/Documents/Art/BlenderArt/tableandappleUV.dae --format c3d --output ~/Documents/Table5.dae
notice the c3d format. use that and your playground can now also recognize the dae. (One other note: if you want to used the dae in the playground you need to put in resources folder of the playground)