NSFetchedResultsController: ReOrder Sections - uitableview

Question

I'm following the example from Apple to setup my sections:
https://developer.apple.com/library/ios/samplecode/DateSectionTitles/Listings/DateSectionTitles_APLEvent_m.html
My sections currently appear in the following order:
Section 0: "Upcoming"
Section 1: "Today"
Section 2: "Past"
Code I use in my NSManagedObject .m file:
#pragma mark - Transient properties
- (NSString *)sectionIdentifier
{
// Create and cache the section identifier on demand.
[self willAccessValueForKey:#"sectionIdentifier"];
NSString *tmp = [self primitiveSectionIdentifier];
[self didAccessValueForKey:#"sectionIdentifier"];
if (!tmp)
{
NSDate *dateToCompare = [self getUTCFormateDate:[self startDate]];
NSLog(#"********Date To Compare****** %#", dateToCompare);
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDate* now = [NSDate date];
NSDateFormatter *format = [[NSDateFormatter alloc] init];
format.dateFormat = #"dd-MM-yyyy";
NSString *stringDate = [format stringFromDate:now];
NSDate *todaysDate = [format dateFromString:stringDate];
NSInteger differenceInDays =
[calendar ordinalityOfUnit:NSDayCalendarUnit inUnit:NSEraCalendarUnit forDate:dateToCompare] -
[calendar ordinalityOfUnit:NSDayCalendarUnit inUnit:NSEraCalendarUnit forDate:todaysDate];
NSString *sectionString;
if (differenceInDays == 0)
{
sectionString = kSectionIDToday;
}
else if (differenceInDays < 0)
{
sectionString = kSectionIDPast;
}
else if (differenceInDays > 0)
{
sectionString = kSectionIDUpcoming;
}
tmp = sectionString;
[self setPrimitiveSectionIdentifier:tmp];
}
return tmp;
}
-(NSDate *)getUTCFormateDate:(NSDate *)localDate
{
NSDateFormatter *dateFormatter;
if (!dateFormatter)
{
dateFormatter = [[NSDateFormatter alloc] init];
}
NSTimeZone *timeZone = [NSTimeZone timeZoneWithName:#"UTC"];
[dateFormatter setTimeZone:timeZone];
[dateFormatter setDateFormat:#"yyyy-MM-dd"];
NSString *dateString = [dateFormatter stringFromDate:localDate];
NSDate *dateFromString = [[NSDate alloc] init];
dateFromString = [dateFormatter dateFromString:dateString];
return dateFromString;
}
#pragma mark - Time stamp setter
- (void)setStartDate:(NSDate *)newDate
{
// If the time stamp changes, the section identifier become invalid.
[self willChangeValueForKey:#"startDate"];
[self setPrimitiveStartDate:newDate];
[self didChangeValueForKey:#"startDate"];
[self setPrimitiveSectionIdentifier:nil];
}
#pragma mark - Key path dependencies
+ (NSSet *)keyPathsForValuesAffectingSectionIdentifier
{
// If the value of timeStamp changes, the section identifier may change as well.
return [NSSet setWithObject:#"startDate"];
}
In my tableViewController, I setup the NSFetchedResults as following:
- (NSFetchedResultsController *)fetchedResultsController
{
if(_fetchedResultsController!=nil)
{
return _fetchedResultsController;
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Entity"
inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSSortDescriptor *firstSort = [[NSSortDescriptor alloc] initWithKey:#"startDate"
ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc]initWithObjects:firstSort,nil];
[fetchRequest setSortDescriptors:sortDescriptors];
self.fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchRequest
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:#"sectionIdentifier"
cacheName:nil];
self.fetchedResultsController.delegate = self;
return self.fetchedResultsController;
}
Question 1: How do I get the sections to appear in the following order:
Section 0: Today
Section 1: Upcoming
Section 2: Past
Question 2: Within each section, how do I sort the rows based on an attribute called "modified" in each object?

Answer 1

Both section and row ordering is 100% dependent upon the sort descriptors. You want your first sort descriptor to sort everything into the proper section and then your following sort descriptors will sort the rows within the sections.
For example, if you wanted three sections based off of "group" and then you wanted the rows sorted by name inside of the group you would add the sort descriptors as:
NSArray *descriptors = #[[NSSortDescriptor sortDescriptorWithKey:#"group" ascending:YES], [NSSortDescriptor sortDescriptorWithKey:#"name" ascending:YES]];
[fetchRequest setSortDescriptors:descriptors];
Your section key for your NSFetchedResultsController will also need to match your first NSSortDescriptor.