iphone - Cocos2d中的倒数计时器？

Question

我正在尝试在cocos2d中创建一个倒数计时器，但我无能为力，想解决此问题，我的代码在此以下，也许逻辑是错误的，但我无法解决。

-(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

您的int countTime = 20;每次都会声明为20。而且，您的while循环将以系统可以更新CCLabel的速度尽 express 减countTimer。如果您尝试执行一个真正的计时器，则只希望在调用countDown:时将其递减。不在while循环中。

尝试这个:

@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