Countdown timer in cocos2d? - iphone

Question

I'm trying to create a countdown timer in cocos2d, but I can not help and would like to resolve this problem, my code is below this, perhaps the logic is wrong but I can not fix.
-(id) init
{
// always call "super" init
// Apple recommends to re-assign "self" with the "super" return value
if( (self=[super init] )) {
CCSprite *background = [CCSprite spriteWithFile:#"backgame.png"];
CGSize size = [[CCDirector sharedDirector] winSize];
[background setPosition:ccp(size.width/2, size.height/2)];
[self addChild: background];
[self schedule:#selector(countDown:)];
}
return self;
}
-(void)countDown:(ccTime)delta
{
CCLabel *text = [CCLabel labelWithString:#" "
fontName:#"BallsoOnTheRampage" fontSize:46];
text.position = ccp(160,455);
text.color = ccYELLOW;
[self addChild:text];
int countTime = 20;
while (countTime != 0) {
countTime -= 1;
[text setString:[NSString stringWithFormat:#"%i", countTime]];
}
}

Answer 1

Your int countTime = 20; is declaring itself every time to be 20. Also, your while loop will decrement the countTimer as fast as the system can update the CCLabel. If you're trying to do a real timer, you want it to decrement ONLY when countDown: is called. Not during a while-loop.
Try this:
#interface MyScene : CCLayer
{
CCLabel *_text;
}
#property (nonatomic, retain) int countTime;
#end
#implementation MyScene
#synthesize countTime = _countTime;
-(id) init {
if( (self=[super init] )) {
CCSprite *background = [CCSprite spriteWithFile:#"backgame.png"];
CGSize size = [[CCDirector sharedDirector] winSize];
[background setPosition:ccp(size.width/2, size.height/2)];
[self addChild: background];
_countTime = 20;
_text = [CCLabel labelWithString:[NSString stringWithFormat:#"%i", self.countTime]
fontName:#"BallsoOnTheRampage" fontSize:46];
text.position = ccp(160,455);
text.color = ccYELLOW;
[self addChild:_text];
[self schedule:#selector(countDown:) interval:0.5f];// 0.5second intervals
}
return self;
}
-(void)countDown:(ccTime)delta {
self.countTime--;
[_text setString:[NSString stringWithFormat:#"%i", self.countTime]];
if (self.countTime <= 0) {
[self unschedule:#selector(countDown:)];
}
}
#end

Answer 2

Your count allways becomes 20 in your countDown.
You should also move this to your init:
CCLabel *text = [CCLabel labelWithString:#" "
fontName:#"BallsoOnTheRampage" fontSize:46];
text.position = ccp(160,455);
text.color = ccYELLOW;
[self addChild:text];
Then you should use:
[self schedule:#selector(countDown:) interval:1.0f];
Then instead of using CCLabel you should use CCLabelBMFont. It's much faster :)