cocos2D随机数组无法调用

创建了一个数组，其中包括红黄绿（321）三个颜色，根据用户点击随机选择一个数字，然后在屏幕上显示对应的颜色，然后系统选择最后输入的颜色，但是我写的代码没有实现这样的功能：

-(void)CreateEnemy:(ccTime)dt{
CCSprite *Enemy;
int a;
if (colorArray != nil) {
    a = arc4random()% [colorArray count];
}
int y = [[colorArray objectAtIndex:a] integerValue];
if (y == 1) {
    Enemy = [CCSprite spriteWithFile:@"GreenBall.png"];
    int x = arc4random()%320;
    Enemy.position = ccp(x, 530);
    id action = [CCMoveTo actionWithDuration:3 position:ccp(x, -30)];
    [Enemy runAction:[CCSequence actions:action, [CCCallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)], nil]];
    [enemyArray addObject:Enemy];
    [self addChild:Enemy z:2 tag:1];
    NSLog(@"Green Enemy Attack!!");
}
else if (y == 2) {
    Enemy = [CCSprite spriteWithFile:@"YellowBall.png"];
    int x = arc4random()%320;
    Enemy.position = ccp(x, 530);
    id action = [CCMoveTo actionWithDuration:3 position:ccp(x, -30)];
    [Enemy runAction:[CCSequence actions:action, [CCCallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)], nil]];
    [enemyArray addObject:Enemy];
    [self addChild:Enemy z:2 tag:1];
    NSLog(@"Yellow Enemy Attack!!");
}
else if (y == 3) {
    Enemy = [CCSprite spriteWithFile:@"RedBall.png"];
    int x = arc4random()%320;
    Enemy.position = ccp(x, 530);
    id action = [CCMoveTo actionWithDuration:3 position:ccp(x, -30)];
    [Enemy runAction:[CCSequence actions:action, [CCCallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)], nil]];
    [enemyArray addObject:Enemy];
    [self addChild:Enemy z:2 tag:1];
    NSLog(@"Red Enemy Attack!!");
}
}

其中Y是一个随机选择数。

在这段代码中

if (colorArray != nil) {
   a = arc4random()% [colorArray count];
}
int y = [[colorArray objectAtIndex:a] integerValue];

[colorArray count]很有可能没有你需要的值, 因此arc4random只能返回0 (或一组有限的值).

如果你在计算a的值之前加上一个 NSLog跟踪, 就可以估计[colorArray count]的值了.