Category on NSString to enumerate a string's substrings that match another string

gistfile1.m

#import <Foundation/Foundation.h>

@interface NSString (PRHEnumerateMatches)

- (NSUInteger) enumerateSubstringsMatchingString_PRH:(NSString *)otherString
	options:(NSStringCompareOptions)mask
	usingBlock:(void (^)(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop))block;

@end

static void test(NSString *stringToFind, NSString *stringToSearch, NSStringCompareOptions options);

int main(int argc, char *argv[]) {
	@autoreleasepool {
		NSString *stringToFind, *stringToSearch;

		stringToFind = @"and";
		stringToSearch = @"One, two! One, two! And through and through\n"
			@"The vorpal blade went snicker-snack!\n"
			@"He left it dead, and with its head\n"
			@"He went galumphing back.";
		test(stringToFind, stringToSearch, NSCaseInsensitiveSearch);

		stringToSearch = @"Hello world!";
		stringToFind = @"world!";
		test(stringToFind, stringToSearch, 0);

		stringToSearch = @"Hello world";
		stringToFind = @"world!";
		test(stringToFind, stringToSearch, 0);
	}
	return EXIT_SUCCESS;
}

static void test(NSString *stringToFind, NSString *stringToSearch, NSStringCompareOptions options) {
	void (^block)(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) = ^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop){
		NSLog(@"%lu-character string[%lu:%lu] = '%@'", stringToSearch.length, substringRange.location, NSMaxRange(substringRange), substring);
	};
	NSUInteger count = [stringToSearch enumerateSubstringsMatchingString_PRH:stringToFind
		options:options
		usingBlock:block];
	NSLog(@"Number of matches: %lu", count);
}

@implementation NSString (PRHEnumerateMatches)

- (NSUInteger) enumerateSubstringsMatchingString_PRH:(NSString *)stringToFind
	options:(NSStringCompareOptions)mask
	usingBlock:(void (^)(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop))block
{
	NSUInteger count = 0;

	NSUInteger selfLength = self.length;
	NSRange searchRange = { 0, selfLength };
	NSRange foundRange;
	BOOL stop = NO;
	while (( ! stop ) && (foundRange = [self rangeOfString:stringToFind options:mask range:searchRange]).location != NSNotFound) {
		++count;
		if (block != NULL) {
			@autoreleasepool {
				NSString *substring = [self substringWithRange:foundRange];
				block(substring, foundRange, /*TODO include terminators and separators in enclosingRange as described in enumerateSubstringsWithOptions:: docs*/ foundRange, &stop);
			}
		}
		searchRange.location = NSMaxRange(foundRange);
		if (searchRange.location >= self.length)
			break;
		searchRange.length = selfLength - searchRange.location;
	}

	return count;
}

@end