UITableView scroll index for array of <FBGraphUser> objects - ios

Question

Really stumped with this need some help! I'm creating a subclass of a UITableViewController to display a list of FB Friends (FBFriendPickerViewController has several limitations for me). I'm able to retrieve an array of id and sort them alphabetically.
However, still can't figure out a way from here to create a separate dictionary to section the FB users into alphabetical sections for indexing.
-(void)captureFacebookFriendUsers
{
//Issue a Facebook Graph API request
NSLog(#"%#", NSStringFromSelector(_cmd));
[FBRequestConnection startForMyFriendsWithCompletionHandler:^(FBRequestConnection *connection, id result, NSError *error){
if (!error) {
NSLog(#"No error requesting friends");
friendsObjects = [result objectForKey:#"data"]; //Objects are id<FBGraphUser>
friendsNames = [NSMutableArray arrayWithCapacity:friendsObjects.count];
NSMutableArray *friendIds = [NSMutableArray arrayWithCapacity:friendsObjects.count];
//Create a list of friends' Facebook IDs
NSSortDescriptor *firstNameDescriptor = [[NSSortDescriptor alloc]initWithKey:#"first_name" ascending:YES];
friendsObjects = [friendsObjects sortedArrayUsingDescriptors:#[firstNameDescriptor]];
for (NSDictionary *friendObject in friendsObjects) {
[friendIds addObject:[friendObject objectForKey:#"id"]];
[friendsNames addObject:[friendObject objectForKey:#"first_name"]];
}
}
Thanks for taking time to read through this!

Answer 1

Andris's code is excellent, but you don't need to create a separate Person class for this to work. Simply use NSDictionary in place of Person class as follows:
First, create your dictionary - I do this in the View Controller from which I am about to call the table view as part of my button action. You'll also need to declare an NSArray *friends and an NSNumber *friendsCount property in both of your .h files (for your initial view controller and for your table view controller) and synthesize as _friends _friendCount.
- (IBAction)btnAddFriendsTapped:(UIBarButtonItem *)sender {
if (FBSession.activeSession.isOpen){
__block NSArray *friendsArray = [[NSArray alloc]init];
__block NSNumber *friendsArrayCount = [[NSNumber alloc]init];
FBRequest* friendsRequest = [FBRequest requestForMyFriends];
[friendsRequest startWithCompletionHandler: ^(FBRequestConnection *connection,
NSDictionary* result,
NSError *error) {
friendsArray = [result objectForKey:#"data"];
friendsArrayCount = [NSNumber numberWithInt:friendsArray.count];
NSLog(#"Found: %i friends", [friendsArrayCount intValue]);
for (NSDictionary<FBGraphUser>* friend in friendsArray) {
NSLog(#"I have a friend named %# with id %#", friend.name, friend.id);
_friends = [NSArray arrayWithArray:friendsArray];
_friendCount = [NSNumber numberWithInt:[friendsArrayCount intValue]];
}
[self performSegueWithIdentifier:#"friendListSegue" sender:self];
}];
}
Then in the prepareForSegue method pass your dictionary to the Table View Controller not forgetting to import your table view controller header file first.
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"friendListSegue"]){
BJFriendListTVC* listOfFriends = segue.destinationViewController;
listOfFriends.friends = _friends;
listOfFriends.friendCount = _friendCount;
}
}
Finally, taking Andris's table code replace the Person class
// Put friends into the appropriate sections
for (NSDictionary<FBGraphUser> *friend in self.friends) {
// Ask the collation which section number the friend name belongs in
NSInteger sectionNumber = [self.collation sectionForObject:friend collationStringSelector:#selector(name)];
// Get the array for that section.
NSMutableArray *sectionFriends = [newSectionsArray objectAtIndex:sectionNumber];
// Add the friend to the section.
[sectionFriends addObject:friend];
}
then when you configure the cell:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
NSDictionary<FBGraphUser> *person = [[self.sectionsArray objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
cell.textLabel.text = person.name;
return cell;
}

Answer 2

You'll need to use UILocalizedIndexedCollation for this and call [self.collation sectionForObject:friend collationStringSelector:#selector(name)] to get the index of the section that corresponds to friend name for the locale of the device.
To do that you'll need to store the friend data in a class that has a property "name" (there might be a way to keep using NSDictionary for friend data that I am not aware of).
Here is some code:
// View Controller code
- (void)viewDidLoad
{
[super viewDidLoad];
[self condigureSections];
}
- (void)configureSections
{
// UILocalizedIndexedCollation
self.collation = [UILocalizedIndexedCollation currentCollation];
NSInteger index, sectionTitlesCount = [[self.collation sectionTitles] count];
// new sections with data
NSMutableArray *newSectionsArray = [[NSMutableArray alloc] initWithCapacity:sectionTitlesCount];
// allocate data array for each of the sections
for (index = 0; index < sectionTitlesCount; index++) {
NSMutableArray *array = [[NSMutableArray alloc] init];
[newSectionsArray addObject:array];
}
// Put friends into the appropriate sections
for (Person *friend in self.friends) {
// Ask the collation which section number the friend name belongs in
NSInteger sectionNumber = [self.collation sectionForObject:friend collationStringSelector:#selector(name)];
// Get the array for that section.
NSMutableArray *sectionFriends = [newSectionsArray objectAtIndex:sectionNumber];
// Add the friend to the section.
[sectionFriends addObject:friend];
}
// Now that all the data's in place, each section array needs to be sorted.
for (index = 0; index < sectionTitlesCount; index++) {
NSMutableArray *friendsArrayForSection = [newSectionsArray objectAtIndex:index];
NSArray *sortedFriendsArrayForSection = [self.collation sortedArrayFromArray:friendsArrayForSection collationStringSelector:#selector(name)];
// Replace the existing array with the sorted array.
[newSectionsArray replaceObjectAtIndex:index withObject:sortedFriendsArrayForSection];
}
self.sectionsArray = newSectionsArray;
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return [self.sectionsArray count];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
return [[self.collation sectionTitles] objectAtIndex:section];
}
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
return [self.collation sectionIndexTitles];
}
- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index
{
return [self.collation sectionForSectionIndexTitleAtIndex:index];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [[self.sectionsArray objectAtIndex:section] count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
....
Person *person = [[self.sectionsArray objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
....
cell.textLabel.text = person.name;
....
return cell;
}
// Store friend data in a class Person so that we could pass the object to
// - (NSInteger)sectionForObject:(id)object collationStringSelector:(SEL)selector
// Example Person.h
#interface Person : NSObject
#property (nonatomic, copy) NSString *id;
#property (nonatomic, copy) NSString *name;
#property (nonatomic, copy) NSString *pictureUrl;
- (id)initWithId:(NSString *)id name:(NSString *)name picture:(NSString *)picUrl;
#end