NSString+Cheddar.m

//
//  NSString+Cheddar.m
//  Cheddar
//
//  Created by Sam Soffes on 6/10/12.
//  Copyright (c) 2012 Nothing Magical. All rights reserved.
//

#import "NSString+Cheddar.h"

@implementation NSString (Cheddar)

- (NSRange)composedRangeWithRange:(NSRange)range {
	// We're going to make a new range that takes into account surrogate unicode pairs (composed characters)
	__block NSRange adjustedRange = range;
	
	// Adjust the location
	[self enumerateSubstringsInRange:NSMakeRange(0, range.location + 1) options:NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
		// If they string the iterator found is greater than 1 in length, add that to range location.
		// This means that there is a composed character before where the range starts who's length is greater than 1.
		adjustedRange.location += substring.length - 1;
	}];
	
	
	// Adjust the length
	NSInteger length = self.length;
	
	// Count how many times we iterate so we only iterate over what we care about.
	__block NSInteger count = 0;
	[self enumerateSubstringsInRange:NSMakeRange(adjustedRange.location, length - adjustedRange.location) options:NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
		// If they string the iterator found is greater than 1 in length, add that to range length.
		// This means that there is a composed character inside of the range starts who's length is greater than 1.
		adjustedRange.length += substring.length - 1;
		
		// Add one to the count
		count++;
		
		// If we have iterated as many times as the original length, stop.
		if (range.length == count) {
			*stop = YES;
		}
	}];
	
	// Make sure we don't make an invalid range. This should never happen, but let's play it safe anyway.
	if (adjustedRange.location + adjustedRange.length > length) {
		adjustedRange.length = length - adjustedRange.location - 1;
	}
	
	// Return the adjusted range
	return adjustedRange;
}


- (NSString *)composedSubstringWithRange:(NSRange)range {
	// Return a substring using a composed range so surrogate unicode pairs (composed characters) count as 1 in the
	// range instead of however many unichars they actually are.
	return [self substringWithRange:[self composedRangeWithRange:range]];
}

@end