Unable to segue using an accessory indicator - ios

Question

I have a segue with three transitions (see code below). The first from a button. That works perfectly. The second by tapping on the cell in a table view. That one works perfectly too. The third is an accessory button in the tableview cell. This one opens the proper view controller, but does not pass a reference to the patient as I have coded. I have verified this by an NSLog statement in the viewDidLoad of the new view controller and it shows patient as being null.
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([[segue identifier] isEqualToString:#"addPatient"]) {
// to add a new patient (selection segue)
UINavigationController *navigationController = segue.destinationViewController;
RXAddPatientViewController *addPatientViewController = (RXAddPatientViewController*)navigationController.topViewController;
Patient *addPatient = [NSEntityDescription insertNewObjectForEntityForName:#"Patient" inManagedObjectContext:[self managedObjectContext]];
addPatientViewController.addPatient = addPatient;
}
if ([[segue identifier] isEqualToString:#"toPrescriptions"]) {
// to view prescriptions for the selected patient (selection segue)
RXPrescriptionsViewController *prescriptionViewController = [segue destinationViewController];
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
Patient *selectedPatient = (Patient*) [self.fetchedResultsController objectAtIndexPath:indexPath];
prescriptionViewController.selectedPatient = selectedPatient;
NSLog(#"Selected Patient is %#", selectedPatient.patientFirstName);
}
if ([[segue identifier] isEqualToString:#"editPatient"]) {
// to edit the selected patient (accessory action)
UINavigationController *navigationController = segue.destinationViewController;
RXEditPatientViewController *editPatientViewController = (RXEditPatientViewController*)navigationController.topViewController;
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
Patient *editPatient = (Patient*) [self.fetchedResultsController objectAtIndexPath:indexPath];
// passing a reference to the editPatientViewController
editPatientViewController.editPatient = editPatient;
NSLog(#"Selected patient is %#", editPatient.patientFirstName);
}
}

Answer 1

The indexPathForSelectedRow will be null when you click on the accessory button because you're not selecting the row. However, the sender argument in prepareForSegue:sender: will be the cell that the accessory button is contained in. So, you should use the following method to get the indexPath (notice that I changed the typing of the argument to UITableViewCell from id):
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(UITableViewCell *)sender {
if ([[segue identifier] isEqualToString:#"editPatient"]) {
// to edit the selected patient (accessory action)
UINavigationController *navigationController = segue.destinationViewController;
RXEditPatientViewController *editPatientViewController = (RXEditPatientViewController*)navigationController.topViewController;
NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
Patient *editPatient = (Patient*) [self.fetchedResultsController objectAtIndexPath:indexPath];
// passing a reference to the editPatientViewController
editPatientViewController.editPatient = editPatient;
NSLog(#"Selected patient is %#", editPatient.patientFirstName);
}