Overview

TLIndexPathController is TLIndexPathTools' version of NSFetchedResultsController. It should not come as a surprise, then, that you must use this class if you want to integrate with Core Data.

Although it primarily exists for Core Data integration, TLIndexPathController works interchangeably with NSFetchRequest or plain ‘ol arrays of arbitrary data. Thus, if you choose to standardize your view controllers on TLIndexPathController, it is possible to have a common programming model across all of your table and collection views.

TLIndexPathController also makes a few nice improvements relative to NSFetchedResultsController:

• Items do not need to be presorted by section. The data model handles organizing sections.
• Changes to your fetch request are animated. So you can get animated sorting and filtering.
• There is only one delegate method to implement (versus five for NSFetchedResultsController).

The basic template for using TLIndexPathController in a (table) view controller is as follows:

#import <UIKit/UIKit.h>
#import "TLIndexPathController.h"
@interface ViewController : UITableViewController TLIndexPathControllerDelegate
@end

#import "ViewController.h"
@interface ViewController ()
@property (strong, nonatomic) TLIndexPathController *indexPathController;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.indexPathController = [[TLIndexPathController alloc] init];
}

#pragma mark - UITableViewDataSource

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return self.indexPathController.dataModel.numberOfSections;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [self.indexPathController.dataModel numberOfRowsInSection:section];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];
    id item = [self.indexPathController.dataModel itemAtIndexPath:indexPath];
    //configure cell using data item
    return cell;
}

#pragma mark - TLIndexPathControllerDelegate

- (void)controller:(TLIndexPathController *)controller didUpdateDataModel:(TLIndexPathUpdates *)updates
{
    [updates performBatchUpdatesOnTableView:self.tableView withRowAnimation:UITableViewRowAnimationFade];
}

@end

This template works with plain arrays or NSFetchRequests. With plain arrays, you simply set the dataModel property of the controller (or set the items property and get a default data model). With NSFetchRequests, you set the fetchRequest property and call performFetch:. From then on, the controller updates the data model interinally every time the fetch results change (using an internal instance of NSFetchedResultsController and responding to controllerDidChangeContent messages).

In either case, whether you explicitly set a data model or the controller converts a fetch result into a data model, the controller creates the TLIndexPathUpdates object for you and passes it to the delegate, giving you an opportunity to perform batch updates:

- (void)controller:(TLIndexPathController *)controller didUpdateDataModel:(TLIndexPathUpdates *)updates
{
    [updates performBatchUpdatesOnTableView:self.tableView withRowAnimation:UITableViewRowAnimationFade];
}