Question

I have a string, and I want to search words (tags) that begin with “#” and end with “.” or “,” or ” ” I found this online, but is limited because:
– You can find a single word in the string (although there are more words)
– “RangeOfString” does not allow multiple choices

NSString *stringText = @"test #hello #world";
NSString *result = nil;

// Determine  "#"
NSRange hashRange = [stringText rangeOfString:@"#" options:NSCaseInsensitiveSearch];
if (hashRange.location != NSNotFound)
{
    // Determine " " location according to "#" location
    NSRange endHashRange;

    endHashRange.location = hashRange.length + hashRange.location;
    endHashRange.length   = [stringText length] - endHashRange.location;
    endHashRange = [stringText rangeOfString:@" " options:NSCaseInsensitiveSearch range:endHashRange];

    if (endHashRange.location != NSNotFound)
    {
        // Tags found: retrieve string between them
        hashRange.location += hashRange.length;
        hashRange.length = endHashRange.location - hashRange.location;

        result = [stringText substringWithRange:hashRange];
    }
}

you have idea how can I do?

Thank you!

Answer 1

You can use NSRegularExpression class, like this:

NSError *error = NULL;
NSRegularExpression *tags = [NSRegularExpression
    regularExpressionWithPattern:@"[#]([^, .]+)([, .]|$)"
    options:NSRegularExpressionCaseInsensitive
    error:&error];
NSArray *matches = [tags matchesInString:str options:0 range:NSMakeRange(0, str.length)];

for (NSTextCheckingResult *match in matches) {
    NSLog(@"%@", [str substringWithRange:[match rangeAtIndex:1]]);
}

You may need to play with your regular expression to get it just right. The reference that I liked describes the grammar of the regex language supported by Apple’s classes.