Cocos2d Random object from array not being called

Question

I have created an array which stores either red, yellow, or green (3, 2, or 1) based on what the user hits. I want the code to choose a random number in the array and display the corresponding color on the screen. However, when the code runs, the program always chooses the last entered color and only shows that color. Code:

-(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!!");
}
}

Y should be a randomly chosen color, but it never is.

Answer 1

In:

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

what is most likely happening is that [colorArray count] has not the value you expect it to have, so that arc4random only returns 0 (or a limited set of values).

If you add an NSLog trace just before calculating the value for a, you can assess the value for [colorArray count].