Since xCode 6.3, sceneKit compiles the collada (.dae) 3D model files a sceneKit optimized format. This format is not compatible with the importer used by the CraftAR Augmented Reality SDK and will produce the following error when trying to load the model:
[ error ] ofxAssimpModelLoader: loadModel(): Collada: File came out empty.
Something is wrong here.
To prevent xCode from compiling your models, you need to tell xCode to load the file into the app Resources as a Data file. You can do this by selecting the file and open the Utilities sidebar in xCode, then under the File Inspector, you will find the Identity and Type section (the first one). The Type selector will by default be set to Digital Asset Exchange (DAE), you just need it to change this option to Data. With this, xCode will not compile the collada xml file and the model will load correctly.