How to mention users with “@” in app like Instagram

Question

I am creating an app that has photo sharing, and I am trying to add in the functionality to mention (or tag) users. Twitter is what originally starting using \"@\" with a userna

Answer 1

Listen to the input on iOS. When the user types an @, followed by a character, make a call to an url on your server (/user/lookup/?username=joe for example) that routes to a view which looks up up users beginning with joe. Return it as json and display it in a dropdown.

Source: How to mention users with "@" in app like Instagram

Answer 2

You can try something like this in the UITextView delegate:

- (void)textViewDidChange:(UITextView *)textView
{
    _words = [self.textView.text componentsSeparatedByString:@" "];
    NSPredicate* predicate = [NSPredicate predicateWithFormat:@"SELF BEGINSWITH[cd] '@'"];
    NSArray* names = [_words filteredArrayUsingPredicate:predicate];
    if (_oldArray)
    {
        NSMutableSet* set1 = [NSMutableSet setWithArray:names];
        NSMutableSet* set2 = [NSMutableSet setWithArray:_oldArray];
        [set1 minusSet:set2];
        if (set1.count > 0)
            NSLog(@"Results %@", set1);
    }
    _oldArray = [[NSArray alloc] initWithArray:names];
}

where _words, _searchResults and _oldArray are NSArrays.