Today I got a weird exception in the Xcode console of my iOS project:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Cannot perform object mapping without a source object to map from'
Turns out I had a couple of missing commas in my JSON. In case your editor doesn't validate JSON, have a look at this online JSON editor.
When I fixed that, I got the same error again. This time, I opened the file in vi, which showed that there were a number of control characters (CTRL-P) in the JSON file:
When I removed those, the error disappeared.