Text Typing Effect in iPhone cocos2d Game

In many games, when a character is speaking (dialogue),开发者_高级运维 the text has a typing effect, where it looks like you are watching the character type the text.

What would be a good way to achieve this look and (simple) "animation" for an iPhone game which uses cocos2d?

It's good if there's a way to do it with cocos2d, but I'm not completely opposed to layering a UIView subclass (UILabel?) on top of cocos2d's EAGL (OpenGL ES) view.

I ended up using built-in UIKit elements (UILabel) and adding them as subviews to the window.

the built-in UIKit could not works well with cocos2d-built-in UIKit,such as CCLabel,CCSprite.

I would suggest using a CCLabelTTF and CCAction as follows:

- (void) typeText
{
    static NSUInteger currentCharacter = 0;

    // Your instance variable stores the text you want to "type" in it:
    _text;

    // Sorry, I can't remember substring functions, this is pseudo-code:
    NSString *substring = [_text getSubstringFrom:0 to:currentCharacter];

    // Also can't remember how to get length of a string (yipes)
    NSUInteger stringLength = [_text length];

    if (currentCharacter < stringLength)
    {
        CCSequence *loop = [CCSequence actions:[CCDelayTime actionWithDuration:0.3f],[CCCallFunc actionWithTarget:self selector:@selector(typeText)],nil];
        [self runAction:loop];
    }
}

This is untested code. Also, it assumes that the typeText function is implemented in a subclass of CCNode because it calls [self runAction:]