SceneKitAssetImport is small but very handy app for converting any 3d model that is supported by Assimp to SceneKit scene.
The supported formats are: 3d, 3ds, ac, b3d, bvh, cob, dae, dxf, ifc, irr, md2, md5mesh, md5anim, m3sd, nff, obj, off, mesh, xml, ply, q3o, q3s, raw, smd, stl, wrl, xgl, zgl, fbx, md3.
SceneKitAssetImport's license is based on the modified, 3-clause BSD-License.