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

Made a category of NSString for that. It's very simple: Find all words, return all words that start with # to get the hashtags.

Relevant code segment below - rename those methods & the category too...

@implementation NSString (PA)
// all words in a string
-(NSArray *)pa_words {
    return [self componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
}

// only the hashtags
-(NSArray *)pa_hashTags {
    NSArray *words = [self pa_words];
    NSMutableArray *result = [NSMutableArray array];
    for(NSString *word in words) {
        if ([word hasPrefix:@"#"])
            [result addObject:word];
    }
    return result;
}