Program to count frequency of a word in sentence. (Stripping any

FrequencyCounter.m

#import <Foundation/Foundation.h>

void frequencyCounterOfWordsInSentence(NSString *sentence)
{
	NSArray *words = [sentence componentsSeparatedByString:@" "];
	NSMutableDictionary *wordCounterDict = [NSMutableDictionary dictionary];
	for(NSString *word in words)
	{
		// Remove any characters from word which is not from letter character set
		NSString *scrubbedWord = [[word componentsSeparatedByCharactersInSet:[[NSCharacterSet letterCharacterSet] invertedSet]] componentsJoinedByString:@""];
		
		// Increment counter value that we retrieve from Hashmap.
		NSNumber *count = wordCounterDict[scrubbedWord];
		NSUInteger counter = count.unsignedIntegerValue;
		counter++;
		[wordCounterDict setValue:@(counter) forKey:scrubbedWord];
	}
	NSLog(@"%@",wordCounterDict);
}

int main(int argc, char *argv[]) 
{
	@autoreleasepool 
	{
	 	frequencyCounterOfWordsInSentence(@"Grammar. a grammatical unit of one or more words that expresses an independent statement, question, request, command, exclamation, etc., and that typically has a subject as well as a predicate, as in John is here. or Is John here? In print or writing, a sentence typically begins with a capital letter and ends with appropriate punctuation; in speech it displays recognizable, communicative intonation patterns and is often marked by preceding and following pauses");
	}
}