parsing string starting with # and # in objective-C - iphone

Question

So I am trying to parse a string that has the following format:
baz#marroon#red#blue #big#cat#dog
or, it can also be separated by spaces:
baz #marroon #red #blue #big #cat #dog
and here's how I am doing it now:
- (void) parseTagsInComment:(NSString *) comment
{
if ([comment length] > 0){
NSArray * stringArray = [comment componentsSeparatedByString:#" "];
for (NSString * word in stringArray){
}
}
}
I've got the components separated by space working, but what if it has no space.. how do I iterate through these words? I was thinking of using regex.. but I have no idea on how to write such regex in objective-C. Any idea, for a regex that would cover both of these cases?
Here's my first attempt:
NSError * error;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"(#|#)\\S+" options:NSRegularExpressionCaseInsensitive error:&error];
NSArray* wordArray = [regex matchesInString:comment
options:0 range:NSMakeRange(0, [comment length])];
for (NSString * word in wordArray){
}
Which doesn't work.. I think my regex is wrong.

Answer 1

Here is a way to do it using NSScanner that puts the separated strings and a string representation of their ranges into an array (this assumes that your original string started with a # -- if it doesn't and you need it to, then just prepend the hash to the string at the start).
NSMutableArray *array = [NSMutableArray array];
NSString *str = #"#baz#marroon#red#blue #big#cat#dog";
NSScanner *scanner = [NSScanner scannerWithString:str];
NSCharacterSet *searchSet = [NSCharacterSet characterSetWithCharactersInString:#"##"];
NSString *outputString;
while (![scanner isAtEnd]) {
[scanner scanUpToCharactersFromSet:searchSet intoString:nil];
[scanner scanCharactersFromSet:searchSet intoString:&outputString];
NSString *symbol = [outputString copy];
[scanner scanUpToCharactersFromSet:searchSet intoString:&outputString];
NSString *wholePiece = [[symbol stringByAppendingString:outputString]stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
NSString *rangeString = NSStringFromRange([str rangeOfString:wholePiece]);
[array addObject:wholePiece];
[array addObject:rangeString];
}
NSLog(#"%#",array);

Answer 2

I think the regular expression you really want is [##]?\\w+. It will find groups of letters optionally preceded by an # or #. Your expression wouldn't work because it looks for any non-space character, which includes # and #. (Depending on what can be in the "words," you might want something more or less specific than \w, but it isn't clear from the question.)

Answer 3

If you need the ranges, then NSRegularExpression probably works well:
NSString *comment = #"#baz#marroon#red#blue #big#cat#dog";
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"[##]\\w+" options:0 error:nil];
NSArray* wordArray = [regex matchesInString:comment
options:0
range:NSMakeRange(0, [comment length])];
for (NSTextCheckingResult *result in wordArray)
NSLog(#"%#", [comment substringWithRange:result.range]);
Or, [##][a-zA-z]+ works if you're ok with ASCII alpha words only.