ios - How to implement table sections with core data

Question

I am using core data in my iOS app. I have a tableview to show the data from an entity called persons. The entity persons has several attributes, on of them is "date". I would like to create 5 permanent sections in the table view (0.Today, 1.Tomorrow, 2.This week, 3.This month, 4.Upcoming), then I want the data to be shown on each section depending on the date. I have been searching for this question, but nothing found that could be applied to my app. I kindly request you to tell me the right way to handle it.

This is my code so far:

#import "PersonsTVC.h"
#import "Person.h"

@implementation PersonsTVC
@synthesize fetchedResultsController = __fetchedResultsController;
@synthesize managedObjectContext = __managedObjectContext;
@synthesize selectedPerson;
@synthesize searchResults,titulosseccion;

- (void)setupFetchedResultsController
{
    // 1 - Decide what Entity you want
    NSString *entityName = @"Person"; // Put your entity name here
    NSLog(@"Setting up a Fetched Results Controller for the Entity named %@", entityName);

    // 2 - Request that Entity
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:entityName];

    // 3 - Filter it if you want
    //request.predicate = [NSPredicate predicateWithFormat:@"Person.name = Blah"];

    // 4 - Sort it if you want
    request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"firstname"
                                                                                     ascending:YES
                                                                                      selector:@selector(localizedCaseInsensitiveCompare:)]];
    // 5 - Fetch it
    self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
                                                                        managedObjectContext:self.managedObjectContext
                                                                          sectionNameKeyPath:nil
                                                                                   cacheName:nil];
    [self performFetch];
}



- (void) viewDidLoad
{



    self.searchResults = [NSMutableArray arrayWithCapacity:[[self.fetchedResultsController fetchedObjects] count]];
    [self.tableView reloadData];
}





-(void) viewDidUnload{
    self.searchResults = nil;
}



- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self setupFetchedResultsController];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return [[self.fetchedResultsController sections] count];


}


- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{

    // Perform segue to detail when a SEARCH table cell is touched
    if(tableView == self.searchDisplayController.searchResultsTableView)
    {
        [self performSegueWithIdentifier:@"Person Detail Segue" sender:tableView];
    }

}



- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Persons Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }

    // Configure the cell...
    // Configure the cell...
    Person  *person = nil;

    if (tableView == self.searchDisplayController.searchResultsTableView)
    {
        NSLog(@"Configuring cell to show search results");
        person = [self.searchResults objectAtIndex:indexPath.row];
    }
    else
    {
        NSLog(@"Configuring cell to show normal data");
        person = [self.fetchedResultsController objectAtIndexPath:indexPath];
    }








    NSString *fullname = [NSString stringWithFormat:@"%@ %@", person.firstname, person.surname];
    cell.textLabel.text = person.firstname;
    if ([person.inRole.color isEqual :@"Yellow"])
    {
        cell.imageView.image = [UIImage imageNamed:@"Yellow"];
    }
    if ([person.inRole.color isEqual :@"Black"])
    {
        cell.imageView.image = [UIImage imageNamed:@"Black"];
    }
    if ([person.inRole.color isEqual :@"Grey"])
    {
        cell.imageView.image = [UIImage imageNamed:@"Grey"];
    }
    if ([person.inRole.color isEqual :@"Red"])
    {
        cell.imageView.image = [UIImage imageNamed:@"Red"];
    }
    if ([person.inRole.color isEqual :@"Blue"])
    {
        cell.imageView.image = [UIImage imageNamed:@"Blue"];
    }
    if ([person.inRole.color isEqual :@"Dark Green"])
    {
        cell.imageView.image = [UIImage imageNamed:@"DarkGreen"];
    }
    if ([person.inRole.color isEqual :@"Light Green"])
    {
        cell.imageView.image = [UIImage imageNamed:@"LightGreen"];
    }
    if ([person.inRole.color isEqual :@"Light Blue"])
    {
        cell.imageView.image = [UIImage imageNamed:@"LightBlue"];
    }
    if ([person.inRole.color isEqual :@"Brown"])
    {
        cell.imageView.image = [UIImage imageNamed:@"Brown"];
    }
    if ([person.inRole.color isEqual :@"Dark Orange"])
    {
        cell.imageView.image = [UIImage imageNamed:@"DarkOrange"];



    }

    NSDate *fechasinformat = person.date;
    NSString *fecha0 = [NSString stringWithFormat:@"%@", fechasinformat];


   cell.detailTextLabel.text = fecha0;



    return cell;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    if (tableView == self.searchDisplayController.searchResultsTableView)
    {
        return [self.searchResults count];
    }
    else
    {
        return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];
    }
}


- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

    if (editingStyle == UITableViewCellEditingStyleDelete) {

        [self.tableView beginUpdates]; // Avoid  NSInternalInconsistencyException

        // Delete the person object that was swiped
        Person *personToDelete = [self.fetchedResultsController objectAtIndexPath:indexPath];
        NSLog(@"Deleting (%@)", personToDelete.firstname);
        [self.managedObjectContext deleteObject:personToDelete];
        [self.managedObjectContext save:nil];

        // Delete the (now empty) row on the table
        [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        [self performFetch];

        [self.tableView endUpdates];
    }
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"Add Person Segue"])
    {
        NSLog(@"Setting PersonsTVC as a delegate of PersonDetailTVC");
        PersonDetailTVC *personDetailTVC = segue.destinationViewController;
        personDetailTVC.delegate = self;

        NSLog(@"Creating a new person and passing it to PersonDetailTVC");
        Person *newPerson = [NSEntityDescription insertNewObjectForEntityForName:@"Person"
                                                          inManagedObjectContext:self.managedObjectContext];

        personDetailTVC.person = newPerson;
    }
    else if ([segue.identifier isEqualToString:@"Person Detail Segue"])
    {
        NSLog(@"Setting PersonsTVC as a delegate of PersonDetailTVC");
        PersonDetailTVC *personDetailTVC = segue.destinationViewController;
        personDetailTVC.delegate = self;

        // Store selected Person in selectedPerson property
        if(sender == self.searchDisplayController.searchResultsTableView)
        {
            NSIndexPath *indexPath = [self.searchDisplayController.searchResultsTableView indexPathForSelectedRow];
            self.selectedPerson = [self.searchResults objectAtIndex:[indexPath row]];
        }
        else
        {
            NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
            self.selectedPerson = [self.fetchedResultsController objectAtIndexPath:indexPath];
        }

        NSLog(@"Passing selected person (%@) to PersonDetailTVC",    self.selectedPerson.firstname);
        personDetailTVC.person = self.selectedPerson;
    }
    else
    {
        NSLog(@"Unidentified Segue Attempted!");
    }
}

- (void)theSaveButtonOnThePersonDetailTVCWasTapped:(PersonDetailTVC *)controller
{
    // do something here like refreshing the table or whatever

    // close the delegated view
    [controller.navigationController popViewControllerAnimated:YES];    
}

#pragma mark -
#pragma mark Content Filtering

-(void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope {
    self.searchResults = [[self.fetchedResultsController fetchedObjects] filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
        Person* person = evaluatedObject;
        NSString* firstName = person.firstname;

        //searchText having length < 3 should not be considered
        if (!!searchText && [searchText length] < 3) {
            return YES;
        }

        if ([scope isEqualToString:@"All"] || [firstName isEqualToString:scope])  {
            return ([firstName rangeOfString:searchText].location != NSNotFound);
        }
        return NO; //if nothing matches
    }]];
}

#pragma mark -
#pragma mark UISearchDisplayController Delegate Methods

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString
{
    [self filterContentForSearchText:searchString scope:@"All"];
    return YES;
}

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchScope:(NSInteger)searchOption
{
    [self filterContentForSearchText:[self.searchDisplayController.searchBar text] scope:@"All"];
    return YES;
}



@end

Answer 1

You would have roughly to do the following:

• Add a first sort descriptor on the date attribute to the fetch request.

• Add a transient property "sectionIdentifier" to the Person entity, and implement a custom getter - (NSString *)sectionIdentifier to the Person managed object subclass, that returns "0", "1", "2", "3", or "4", depending on the date attribute of the object.

• Set sectionNameKeyPath:@"sectionIdentifier" in the creation of the fetched results controller.

• Add a titleForHeaderInSection method to the table view controller, that returns "Today", "Tomorrow", ... depending on the section.

The DateSectionTitles sample project from the Apple Developer Library also demonstrates how this works.

The sort descriptors would then look like this:

// First sort descriptor (required for grouping into sections):
NSSortDescriptor *sortByDate = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];
// Second sort descriptor (for the items within each section):
NSSortDescriptor *sortByName = [[NSSortDescriptor alloc] initWithKey:@"firstname" ascending:YES];
[request setSortDescriptors:@[sortByDate, sortByName]];

The getter method for the transient "sectionIdentifier" property would look like (adapted from the "DateSectionTitles" sample code):

- (NSString *)sectionIdentifier
{
    [self willAccessValueForKey:@"sectionIdentifier"];
    NSString *tmp = [self primitiveValueForKey:@"sectionIdentifier"];
    [self didAccessValueForKey:@"sectionIdentifier"];

    if (!tmp)
    {
        NSDate *date = self.date;
        // Using pseudo-code here:
        if ("date is from today") {
            tmp = @"0";
        } else if ("date is from tomorrow") {
            tmp = @"1";
        } else ... // and so on ...

        [self setPrimitiveValue:tmp forKey:@"sectionIdentifier"];
    }
    return tmp;
}

To determine if the date falls on today, tomorrow etc you have to use NSCalendar methods.

The titleForHeaderInSection method would be similar to this (untested, as everything else in this answer):

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    id <NSFetchedResultsSectionInfo> theSection = [[self.fetchedResultsController sections] objectAtIndex:section];

    NSString *sectionName = [theSection name];
    if ([sectionName isEqualToString:@"0"]) {
        return @"Today";
    } else if ([sectionName isEqualToString:@"1"]) {
        return @"Tomorrow";
    } ... // and so on ...
    } else {
        return @"Other";
    }
}