ios - 对象数组的 UITableView 滚动索引

Question

真的很困惑，需要一些帮助!我正在创建 UITableViewController 的子类来显示 FB 好友列表(FBFriendPickerViewController 对我来说有一些限制)。我能够检索 id 数组并按字母顺序对它们进行排序。

但是，仍然无法从这里找到一种方法来创建单独的字典，将 FB 用户分为按字母顺序排列的部分以进行索引。

-(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"]];
        }
}

感谢您花时间阅读本文!

Answer 1

Andris 的代码非常好，但您不需要为此创建一个单独的 Person 类。只需使用 NSDictionary 代替 Person 类，如下所示:

首先，创建您的字典 - 我在 View Controller 中执行此操作，我将从中调用 TableView 作为我的按钮操作的一部分。您还需要在两个 .h 文件(用于初始 View Controller 和 TableView Controller )中声明一个 NSArray *friends 和一个 NSNumber *friendsCount 属性，并合成为 _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];

     }];
}

然后在 prepareForSegue 方法中将您的字典传递给 TableView Controller ，不要忘记先导入您的 TableView Controller 头文件。

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:@"friendListSegue"]){              
    BJFriendListTVC* listOfFriends = segue.destinationViewController;
    listOfFriends.friends = _friends;
    listOfFriends.friendCount = _friendCount;
}

}最后以Andris的表代码替换Person类

// 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];
}

然后当您配置单元时:

- (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;
}