Custom Selector For NSSortDescriptor and NSFetchedResultsController

Question

I am running into a bit of trouble and I was wondering if someone could provide some guidance.

I am attempting to create section headers with the following order: [\

Answer 1

The NSSortDescriptor constructor that you're using attempts to call the specified selector on the objects held at the property named @"states". I'm not sure what this value is, but it looks like they might be NSSortDescriptor objects based on the error you're seeing.

Instead of trying to find a selector on an object which may or may not exist, use the block constructor:

You should also really consider rewriting your comparison with integers or something to make it smaller:

static NSArray *stateOrder = @[@"Push", @"Busy", @"Finished", @"Cancelled"];

NSSortDescriptor *sortStates = [NSSortDescriptor sortDescriptorWithKey:@"states"
                                                    ascending:NO
                                                   comparator:^(id obj1, id obj2) {
  NSInteger state1 = [stateOrder indexOfObject:obj1];
  NSInteger state2 = [stateOrder indexOfObject:obj2];
  if (state1 < state2) {
    return (NSComparisonResult)NSOrderedAscending;
  } else if (state1 > state2) {
    return (NSComparisonResult)NSOrderedDescending;
  }
  return (NSComparisonResult)NSOrderedSame;
}];