How do you detect words that start with “@” or “#” within an NSString?

Question

I\'m building a Twitter iPhone app, and it needs to detect when you enter a hashtag or @-mention within a string in a UITextView.

How do I find all words preceded by

Answer 1

Here's how you can do it using NSPredicate

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.