iOS implementing a "Contact View Controller"

Question

I want to implement something similar to the iPhone's Contact list. I know that there is an address book framework that allows me to access the device's contacts, but I want to use my own contacts stored in my Core Data database.

I am using NSFetchedResultsControllerto fetch and list my contacts on a table view.

However, I can not seem to find a way to get NSFetchedResultsController to display my contacts organized by section, being each section the first letter of each contact's name. Like:

Section A: All contacts that start with the letter A
Section B: All contacts that start with the letter B
etc...

I think that I can do this with the sectionNameKeyPath: parameter in the init method for NSFetchedResultsController, but how am I supposed to use it to achieve my ends?

Answer 1

You have to sort your data first and get a list of "keys" (A, B, C, D, E) for each section. Save these as an NSArray on a property.

Implement this:

// Function to load your data
-(void)dataDidLoad
{
// sort the keys
        self.sortedKeysForUsersWithApp = tSortedKeys;
//
        [self.tableView reloadData];
}
-(UIView*)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
// add a UILabel
    headerLabel.text = [self.sortedKeysForUsersWithApp objectAtIndex:section];
// set the text to the section title
}

-(NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView {
    return [NSArray arrayWithObjects:@"A", @"B", @"C", @"D", @"E", @"F", @"G", @"H", @"I", @"J", @"K", @"L", @"M", @"N", @"O", @"P", @"Q", @"R", @"S", @"T", @"U", @"V", @"W", @"X", @"Y", @"Z", @"#", nil];
}

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

-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    //return self.sortedKeys.count;
    return self.sortedKeysForUsersWithApp.count;
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    NSDictionary *tDictionary = self.sortedUsersWithApp;

    //NSString *key = [self.sortedKeys objectAtIndex:section];
    NSString *key = [self.sortedKeysForUsersWithApp objectAtIndex:section];
    return ((NSArray*)[tDictionary objectForKey:key]).count;
}