Custom Section Name Crashing NSFetchedResultsController
问题 I have a managed object with a dueDate attribute. Instead of displaying using some ugly date string as the section headers of my UITableView I created a transient attribute called "category" and defined it like so: - (NSString*)category { [self willAccessValueForKey:@"category"]; NSString* categoryName; if ([self isOverdue]) { categoryName = @"Overdue"; } else if ([self.finishedDate != nil]) { categoryName = @"Done"; } else { categoryName = @"In Progress"; } [self didAccessValueForKey:@