objective c - 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 the "@" or "#" characters within an NSString?

Thanks for your help!

Answer 1

You can use NSRegularExpression class with a pattern like #w+ (w stands for word characters).

NSError *error = nil;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"#(\w+)" options:0 error:&error];
NSArray *matches = [regex matchesInString:string options:0 range:NSMakeRange(0, string.length)];
for (NSTextCheckingResult *match in matches) {
    NSRange wordRange = [match rangeAtIndex:1];
    NSString* word = [string substringWithRange:wordRange];
    NSLog(@"Found tag %@", word);
}