Swift中的索引超出范围错误

var numberOfPeople = 1 //get from host
var numberAtCounter = 0
func showNames() {

    if peopleInMatch[numberAtCounter] == yourPeerID { //change to peopleinmatcheveryone

        if numberOfPeople == 0 {
            print("hoho")
            personName.isHidden = true
            connect.isHidden = false
            connect.setTitle("PRESS READY", for: UIControlState.normal)
            //change label to ready
        } else {
            numberAtCounter += 1
            numberOfPeople -= 1 // buggy?
            print("\(numberAtCounter)")
            showNames()
        }


    } else {
    personName.text = "TAKE PHOTO OF \(peopleInMatch[numberAtCounter])'s COLOR"
    numberAtCounter += 1
        if numberOfPeople <= 0 {
            personName.isHidden = true
            connect.isHidden = false
            connect.setTitle("PRESS READY", for: UIControlState.normal)
            //change label to ready
        }
    numberOfPeople -= 1 //buggy maybe fixed

    }
}

我在if peopleInMatch[numberAtCounter]==yourPeerID行上得到一个线程1:EXC\u断点错误。我不完全确定索引外是什么意思,也不确定有什么潜在的错误。代码将运行一次,然后函数调用自己,第二次在我上面提到的行中崩溃。我检查了所有的变量,没有一个是零。有什么想法吗?