调用arc4random方法来生成一个敌人但是生成两个敌人

Hello I am making a side scrolling cocos2d app where enemies attack a character. I am using arc4random and a switch statement to spawn the enemies one at a time. This should happen but it instead spawns two at a time. I am a beginner in cocos2d and objective c so I may be missing something simple. Any help is valuable though. Hello I am making a side scrolling cocos2d app