Last Updated: February 25, 2016
·
1.194K
· carlambroselli

CoreDataTableViewController

Subclass this to have a TableView that automatically keeps synchronised with your model.

You just need to:

  • set self.tableView
  • insert @property (nonatomic, strong) NSManagedObjectContext *managedObjectContext; into your header.
  • set self.fetchedResultsController:
- (void)setManagedObjectContext:(NSManagedObjectContext *)managedObjectContext
{
    _managedObjectContext = managedObjectContext;
    if(managedObjectContext) {
        NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"EntityName"];
        request.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"Attribute" ascending:NO], [NSSortDescriptor sortDescriptorWithKey:@"secondAttribute" ascending:NO]];
        request.predicate = [NSPredicate predicateWithFormat:@"x == NO"];

        self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:nil]; // sectionNameKeyPath = KeyPath for the Section Names;
    }else {
        self.fetchedResultsController = nil;
    }
}
  • set the managedObjectContext
//Example
self.fetchedResultsController = nil;
self.managedObjectContext = [[Database sharedInstance] managedObjectContext];

CoreDataTableViewController.h

//
//  CoreDataTableViewController.h
//
// This class mostly just copies the code from NSFetchedResultsController's documentation page
//   into a subclass of UITableViewController.
//
// Just subclass this and set the fetchedResultsController.
// The only UITableViewDataSource method you'll HAVE to implement is tableView:cellForRowAtIndexPath:.
// And you can use the NSFetchedResultsController method objectAtIndexPath: to do it.
//
// Remember that once you create an NSFetchedResultsController, you CANNOT modify its @propertys.
// If you want new fetch parameters (predicate, sorting, etc.),
//  create a NEW NSFetchedResultsController and set this class's fetchedResultsController @property again.
//

#import <UIKit/UIKit.h>
#import <CoreData/CoreData.h>

@interface CoreDataTableViewController : UIViewController <NSFetchedResultsControllerDelegate,UITableViewDelegate, UITableViewDataSource>

@property(nonatomic,retain) UITableView *tableView;

// The controller (this class fetches nothing if this is not set).
@property (strong, nonatomic) NSFetchedResultsController *fetchedResultsController;

// Causes the fetchedResultsController to refetch the data.
// You almost certainly never need to call this.
// The NSFetchedResultsController class observes the context
//  (so if the objects in the context change, you do not need to call performFetch
//   since the NSFetchedResultsController will notice and update the table automatically).
// This will also automatically be called if you change the fetchedResultsController @property.
- (void)performFetch;

// Turn this on before making any changes in the managed object context that
//  are a one-for-one result of the user manipulating rows directly in the table view.
// Such changes cause the context to report them (after a brief delay),
//  and normally our fetchedResultsController would then try to update the table,
//  but that is unnecessary because the changes were made in the table already (by the user)
//  so the fetchedResultsController has nothing to do and needs to ignore those reports.
// Turn this back off after the user has finished the change.
// Note that the effect of setting this to NO actually gets delayed slightly
//  so as to ignore previously-posted, but not-yet-processed context-changed notifications,
//  therefore it is fine to set this to YES at the beginning of, e.g., tableView:moveRowAtIndexPath:toIndexPath:,
//  and then set it back to NO at the end of your implementation of that method.
// It is not necessary (in fact, not desirable) to set this during row deletion or insertion
//  (but definitely for row moves).
@property (nonatomic) BOOL suspendAutomaticTrackingOfChangesInManagedObjectContext;

// Set to YES to get some debugging output in the console.
@property BOOL debug;

@end

CoreDataTableViewController.m

//
//  CoreDataTableViewController.m
//
//

#import "CoreDataTableViewController.h"

@interface CoreDataTableViewController()
@property (nonatomic) BOOL beganUpdates;
@end

@implementation CoreDataTableViewController

#pragma mark - Properties

@synthesize fetchedResultsController = _fetchedResultsController;
@synthesize suspendAutomaticTrackingOfChangesInManagedObjectContext = _suspendAutomaticTrackingOfChangesInManagedObjectContext;
@synthesize debug = _debug;
@synthesize beganUpdates = _beganUpdates;

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

#pragma mark - Fetching

- (void)performFetch
{
    if (self.fetchedResultsController) {
        if (self.fetchedResultsController.fetchRequest.predicate) {
            if (self.debug) NSLog(@"[%@ %@] fetching %@ with predicate: %@", NSStringFromClass([self class]), NSStringFromSelector(_cmd), self.fetchedResultsController.fetchRequest.entityName, self.fetchedResultsController.fetchRequest.predicate);
        } else {
            if (self.debug) NSLog(@"[%@ %@] fetching all %@ (i.e., no predicate)", NSStringFromClass([self class]), NSStringFromSelector(_cmd), self.fetchedResultsController.fetchRequest.entityName);
        }
        NSError *error;
        [self.fetchedResultsController performFetch:&error];
        if (error) NSLog(@"[%@ %@] %@ (%@)", NSStringFromClass([self class]), NSStringFromSelector(_cmd), [error localizedDescription], [error localizedFailureReason]);
    } else {
        if (self.debug) NSLog(@"[%@ %@] no NSFetchedResultsController (yet?)", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
    }
    [self.tableView reloadData];
}

- (void)setFetchedResultsController:(NSFetchedResultsController *)newfrc
{
    NSFetchedResultsController *oldfrc = _fetchedResultsController;
    if (newfrc != oldfrc) {
        _fetchedResultsController = newfrc;
        newfrc.delegate = self;
        if ((!self.title || [self.title isEqualToString:oldfrc.fetchRequest.entity.name]) && (!self.navigationController || !self.navigationItem.title)) {
            self.title = newfrc.fetchRequest.entity.name;
        }
        if (newfrc) {
            if (self.debug) NSLog(@"[%@ %@] %@", NSStringFromClass([self class]), NSStringFromSelector(_cmd), oldfrc ? @"updated" : @"set");
            [self performFetch]; 
        } else {
            if (self.debug) NSLog(@"[%@ %@] reset to nil", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
            [self.tableView reloadData];
        }
    }
}

#pragma mark - UITableViewDataSource

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    return [[[self.fetchedResultsController sections] objectAtIndex:section] name];
}

- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index
{
    return [self.fetchedResultsController sectionForSectionIndexTitle:title atIndex:index];
}

- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
    return [self.fetchedResultsController sectionIndexTitles];
}

#pragma mark - NSFetchedResultsControllerDelegate

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
    if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext) {
        [self.tableView beginUpdates];
        self.beganUpdates = YES;
    }
}

- (void)controller:(NSFetchedResultsController *)controller
  didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex
     forChangeType:(NSFetchedResultsChangeType)type
{
    if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
    {
        switch(type)
        {
            case NSFetchedResultsChangeInsert:
                [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                break;

            case NSFetchedResultsChangeDelete:
                [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                break;
        }
    }
}


- (void)controller:(NSFetchedResultsController *)controller
   didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath
     forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{       
    if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
    {
        switch(type)
        {
            case NSFetchedResultsChangeInsert:
                [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
                break;

            case NSFetchedResultsChangeDelete:
                [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                break;

            case NSFetchedResultsChangeUpdate:
                [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                break;

            case NSFetchedResultsChangeMove:
                [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
                break;
        }
    }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
    if (self.beganUpdates) [self.tableView endUpdates];
}

- (void)endSuspensionOfUpdatesDueToContextChanges
{
    _suspendAutomaticTrackingOfChangesInManagedObjectContext = NO;
}

- (void)setSuspendAutomaticTrackingOfChangesInManagedObjectContext:(BOOL)suspend
{
    if (suspend) {
        _suspendAutomaticTrackingOfChangesInManagedObjectContext = YES;
    } else {
        [self performSelector:@selector(endSuspensionOfUpdatesDueToContextChanges) withObject:0 afterDelay:0];
    }
}

@end

Sample cellForRowAtIndexPath:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    MainlistCell *cell = (MainlistCell*) [tableView dequeueReusableCellWithIdentifier:@"MainlistCell" forIndexPath:indexPath];

    cell.info = [self.fetchedResultsController objectAtIndexPath:indexPath];

    return cell;
}

1 Response
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Thanks for COREDATATABLEVIEWCONTROLLER.M code. Had issues deleting last row!

over 1 year ago ·