“致命错误：指数超出范围”

Question

我们有2个字段，包含消息和密钥。将它们转换为字节并对消息和密钥的每个字节使用^（它可以小于实际消息长度，这就是我们在那里使用％的原因）

@IBOutlet weak var messageToEncrypt: UITextField!
@IBOutlet weak var encryptionKey: UITextField!
@IBOutlet weak var cryptResult: UITextField!
@IBOutlet weak var decryptResult: UITextField!
@IBAction func encryptFunc(sender: AnyObject) {
    let mte = messageToEncrypt.text;
    let kte = encryptionKey.text;
    var mte_byteArray = [UInt8]();
    var kte_byteArray = [UInt8]();

    for char in mte!.utf8{
        mte_byteArray += [char]
    }
    for char1 in kte!.utf8{
        kte_byteArray += [char1]
    }

    var counT: Int =  mte_byteArray.count;
    var cryptedSum = [UInt8](count: counT, repeatedValue: 0);
    for i in 0...mte_byteArray.count{
        cryptedSum[i] = mte_byteArray[i] ^ kte_byteArray[i%kte_byteArray.count];
    }
    print(cryptedSum);
}

这里我有这个问题

for i in 0...mte_byteArray.count{
    cryptedSum[i] = mte_byteArray[i] ^ kte_byteArray[i%kte_byteArray.count];
}

  

致命错误：索引超出范围