Cocos2D CCLabelBMFont that can display two colours, by surrounding [highlighted] sections in [square brackets] for emphasis.

TwoColorText.h

//
//  TwoColorText.h
//  SpaceBotAlpha
//
//  Created by Sarah Smith on 26/08/2014.
//  Copyright (c) 2014 Smithsoft Pty Ltd. All rights reserved.
//  License: https://creativecommons.org/licenses/by-sa/3.0/au/
//
//  Implemented from ideas seen here: http://whitesponge.com/blog/dual-colored-labels-with-cocos2d/
//  but done so as to handle multiple sections of [highlighted] text [not just one].

#import "CCLabelBMFont.h"

@interface TwoColorText : CCLabelBMFont
{
    NSString *_rawText;
    NSString *_highlightColorHexString;
}

@property (nonatomic, strong) CCColor *highlightColor;
@property (nonatomic, strong) NSString *highlightColorHexString;

@end

TwoColorText.m

//
//  TwoColorText.m
//  SpaceBotAlpha
//
//  Created by Sarah Smith on 26/08/2014.
//  Copyright (c) 2014 Smithsoft Pty Ltd. All rights reserved.
//

#import "TwoColorText.h"

NSString *stripSquareBrackets(NSString *theString)
{
    NSMutableString *text = [theString mutableCopy];
    [text replaceOccurrencesOfString:@"[" withString:@"" options:NSCaseInsensitiveSearch
                               range:NSMakeRange(0, [text length])];
    [text replaceOccurrencesOfString:@"]" withString:@"" options:NSCaseInsensitiveSearch
                               range:NSMakeRange(0, [text length])];
    return [text copy];
}

NSString *hexStringFromColor(CCColor *color)
{
    NSInteger r = [color red] * 255.0f;
    NSInteger g = [color green] * 255.0f;
    NSInteger b = [color blue] * 255.0f;
    return [NSString stringWithFormat:@"#%02x%02x%02x", r, g, b];
}

@implementation TwoColorText
{
    BOOL _dirty;
}

@synthesize highlightColor = _highlightColor;
@synthesize highlightColorHexString = _highlightColorHexString;

- (void)update:(CCTime)delta
{
    if (_dirty)
    {
        [self updateHighlightedText];
    }
}

- (NSString *)description
{
    return [NSString stringWithFormat:@"%@ - %@ - %@", [super description], _rawText, [self highlightColorHexString]];
}

-(id) initWithString:(NSString*)theString fntFile:(NSString*)fntFile width:(float)width alignment:(CCTextAlignment)alignment imageOffset:(CGPoint)offset
{
    self = [super initWithString:stripSquareBrackets(theString) fntFile:fntFile width:width alignment:alignment imageOffset:offset];
    if (self)
    {
        _rawText = theString;
        _cascadeColorEnabled = NO;
        _highlightColor = [CCColor colorWithCcColor4b:ccc4(70, 117, 255, 255)];
        _highlightColorHexString = hexStringFromColor(_highlightColor);
        [self updateHighlightedText];
    }
    return self;
}

- (void)setColor:(CCColor *)color
{
    [super setColor:color];
    _dirty = YES;
}

- (void)setColorRGBA:(CCColor *)colorRGBA
{
    [super setColorRGBA:colorRGBA];
    _dirty = YES;
}

- (void)setHighlightColor:(CCColor *)highlightColor
{
    _highlightColor = highlightColor;
    _highlightColorHexString = hexStringFromColor(_highlightColor);
    _dirty = YES;
}

- (void)setHighlightColorHexString:(NSString *)highlightColorHexString
{
    _dirty = YES;
    _highlightColorHexString = highlightColorHexString;
    highlightColorHexString = [highlightColorHexString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    NSUInteger len = [highlightColorHexString length];
    if (len == 0)
    {
        // either nil or @""
        _highlightColor = [CCColor colorWithCcColor4b:ccc4(70, 117, 255, 255)];
        return;
    }
    _highlightColor = nil;
    NSString *hx = @"^#([0-9a-fA-F]{2})([0-9a-fA-F]{2})([0-9a-fA-F]{2})";
    NSRegularExpression *hexColorString = [NSRegularExpression regularExpressionWithPattern:hx options:0 error:nil];
    NSArray *matches = [hexColorString matchesInString:highlightColorHexString options:0 range:NSMakeRange(0, [highlightColorHexString length])];
    if ([matches count] == 1)
    {
        NSUInteger r = 0, g = 0, b = 0;
        NSTextCheckingResult *result = [matches objectAtIndex:0];
        if ([result numberOfRanges] == 4)
        {
            r = strtol([[highlightColorHexString substringWithRange:[result rangeAtIndex:1]] UTF8String], NULL, 16);
            g = strtol([[highlightColorHexString substringWithRange:[result rangeAtIndex:2]] UTF8String], NULL, 16);
            b = strtol([[highlightColorHexString substringWithRange:[result rangeAtIndex:3]] UTF8String], NULL, 16);
            _highlightColor = [CCColor colorWithCcColor3b:ccc3(r, g, b)];
        }
    }
    if (_highlightColor == nil)
    {
        NSLog(@"#### ERROR: bad color %@: expected \"#rrggbb\" where r, g & b are 0-9", highlightColorHexString);
    }
}

- (void)updateHighlightedText
{
    _dirty = NO;
    CCColor *white = [CCColor whiteColor];
    if (_rawText != nil && [_rawText rangeOfString:@"["].location != NSNotFound)
    {
        _cascadeColorEnabled = NO;
        NSUInteger rawLen = [_rawText length];
        NSMutableArray *markers = [NSMutableArray arrayWithCapacity:rawLen];
        for (NSUInteger i = 0; i < rawLen; ++i)
        {
            [markers addObject:@" "];
        }
        NSRange currentRange;
        currentRange.length = rawLen;
        currentRange.location = 0;
        NSCharacterSet *nlcs = [NSCharacterSet newlineCharacterSet];
        while (true)
        {
            NSUInteger linefeed = [_rawText rangeOfCharacterFromSet:nlcs options:0 range:currentRange].location;
            if (linefeed == NSNotFound) break;
            [markers setObject:@"N" atIndexedSubscript:linefeed];
            currentRange.location = linefeed+1;
            currentRange.length = rawLen - currentRange.location;
        }
        currentRange.location = 0;
        currentRange.length = rawLen;
        while (true)
        {
            NSUInteger startBracket = [_rawText rangeOfString:@"[" options:0 range:currentRange].location;
            NSUInteger endBracket = [_rawText rangeOfString:@"]" options:0 range:currentRange].location;
            if (startBracket == NSNotFound || endBracket == NSNotFound) { break; }
            [markers setObject:@"[" atIndexedSubscript:startBracket];
            [markers setObject:@"]" atIndexedSubscript:endBracket];
            currentRange.location = endBracket + 1;
            currentRange.length = rawLen - currentRange.location;
        }
        NSUInteger ix = 0;
        BOOL inHighlight = NO;
        CCColor *col = [self color];
        if (col == nil)
        {
            col = white;
        }
        for (NSString *marker in markers)
        {
            if ([marker isEqualToString:@"["])
            {
                inHighlight = YES;
            }
            else if ([marker isEqualToString:@"]"])
            {
                inHighlight = NO;
            }
            else if ([marker isEqualToString:@"N"])
            {
                //
            }
            else
            {
                CCSprite *charSprite = (CCSprite *)[[self children] objectAtIndex:ix];
                [charSprite setColor:inHighlight ? [self highlightColor] : col];
                ++ix;
            }
        }
    }
    else
    {
        _cascadeColorEnabled = YES;
    }
}

- (void)setString:(NSString *)label
{
    [super setString:stripSquareBrackets(label)];
    _rawText = [label copy];
    _dirty = YES;
}

@end