Thanks for pointing this out! I noticed that it could happen that the completion handler is called twice. But in the simulator it works without problems. I will release an update of the app and hope that this was the reason.

It works when I connect an iPhone to the mac as a camera. If I then disconnect the iPhone again, the app crashes again. An additional check with UIImagePickerController.isCameraDeviceAvailable returns true. CMIOHardware.cpp:124:CMIOObjectHasProperty no object with given ID 666 CMIOHardware.cpp:150:CMIOObjectHasProperty Error: 560947818, failed *** Terminating app due to uncaught exception 'NSInvalidArgumentException',