Split core data table view into sections - ios

Question

Currently my table view loads a long list of items NSMutableArray *certificates;
I want to group these into sections based on the certificateType. So far I have grouped the sections but need add the data to the sections based on the certificateType
The UITableView is populated from core data object Certificate
Can I sort these into sections using the name of cell.textLabel.text = [NSString stringWithFormat:#"%# (%#)", thisCert.certificateType.title, thisCert.title];
Or should I split up NSMutableArray *certificates; into 4 separate arrays
Any advice on best way to approach this would be appreciated
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
LogCmd();
return 4;
}
//Section Titles
-(NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
//Section Text
[[UILabel appearanceWhenContainedIn:[UITableViewHeaderFooterView class], nil] setFont:[UIFont systemFontOfSize:18]];
//Section Titles
NSArray *sectionTitles = [NSArray arrayWithObjects:#"BlueCert", #"GreenCert", #"RedCert", #"OrangeCert", nil];
NSString *result = [sectionTitles objectAtIndex:section];
return result;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
return 60.0f;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if (tableView == self.searchDisplayController.searchResultsTableView) {
return self.searchResults.count;
}
else {
return self.certificates.count;
}
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
LogCmd();
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
cell.textLabel.font = [UIFont boldSystemFontOfSize:14.0f];
cell.imageView.image = [UIImage imageNamed:#"IconFolderOpen"];
}
Certificate *thisCert;
if (tableView == self.searchDisplayController.searchResultsTableView) {
thisCert = (self.searchResults)[indexPath.row];
}
else {
thisCert = (self.certificates)[indexPath.row];
}
cell.textLabel.text = [NSString stringWithFormat:#"%# (%#)", thisCert.certificateType.title, thisCert.title];
cell.detailTextLabel.text = [NSString stringWithFormat:#"Reference: %#", thisCert.reference];
return cell;
}

Answer 1

If your data is dynamic, I suggest that you set up an NSFetchedResultsController.
That way your data is still together in the managed object context, but the data source for the table view can be broken up into sections based on title. Set the sectionNameKeyPath as certificate title for the NSFetchedResultsController. Set a sort descriptor based on certificate title for the NSFetchRequest used to get data into the NSFetchedResultsController.
Implement your view controller as the delegate for the NSFetchedResultsController.
Adding some high level code for elaboration. Most of this code is styled from the book Core Data Data Storage and Management for Ios, OS X, and Icloud by Marcus Zarra.
Assuming you have a managed object context and your are adding properties for NSFetchedResultsController and NSFetchRequest in your view controller
- (NSFetchedResultsController *) certificatesFetchedResultsController{
if(!_certificatesFetchedResultsController){
_certificatesFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:self.certificatesFetchRequest managedObjectContext:self.certitificatesMOC sectionNameKeyPath:#"title" cacheName:nil];
_certificatesFetchedResultsController.delegate = self;
}
return _certificatesFetchedResultsController;
}
- (NSFetchRequest *) certificatesFetchRequest{
if(!_certificatesFetchRequest){
_certificatesFetchRequest = [NSFetchRequest fetchRequestWithEntityName:#"Certificate"];
NSSortDescriptor *sortTitle = [[NSSortDescriptor alloc] initWithKey:#"title" ascending:NO];
[_certificatesFetchRequest setSortDescriptors:#[sortTitle]];
}
return _certificatesFetchRequest;
}
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller{
[self.tableView beginUpdates];
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller{
[self.tableView endUpdates];
}
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type{
switch(type) {
case NSFetchedResultsChangeInsert:
[[self transactionsTblView] insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[[self transactionsTblView] deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath{
NSArray *newArray = #[[NSIndexPath indexPathForItem:newIndexPath.row inSection:newIndexPath.section];
NSArray *oldArray = #[[NSIndexPath indexPathForItem:indexPath.row inSection:indexPath.section];
switch(type) {
case NSFetchedResultsChangeInsert:
[self.transactionsTblView insertRowsAtIndexPaths:newArray withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.transactionsTblView deleteRowsAtIndexPaths:oldArray withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section{
NSManagedObject *object = [self.certificatesFetchedResultsController objectAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:section]];
// Create your section title using data in the managed object and return the UIView
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
NSManagedObject *object = [self.certificatesFetchedResultsController objectAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:section]];
// Configure cell data as per data in managed object
}
Somewhere, initialze the fetched result controller. Maybe in viewDidLoad
[self.certificatesFetchedResultsController performFetch:nil];