It turns out it is because of the following line of code:

NSLog(@"numberOfRowsInSection %@", [sectionInfo numberOfObjects]);

It should be %i because numberOfObjects returns an integer

I did not know that after implemented a NSFetchResultController, I sTILl need to programmatically fetch the data and then call the table view to reloadData

An example:

The stack trace

Delete the working project in shell by accident! Time Machine saved the day

App just mysteriously terminates after core data fetch…