类型字符串不符合协议序列类型 [英] type String does not conform to protocol sequencetype

问题描述

这是代码，我正在尝试制作一个简单的计算器:

Here is the code, I'm trying to make a simple calculator :

@IBAction func btnOperatorInput(sender: UIButton) {
    let op = ("+", "-", "*", "/")

    let nr1 = sender.currentTitle!
    var nr2 = ""
    if sender.currentTitle == nr1{

        display.text! = self.display.text! + nr1
        nrTaped = true

    } else if sender.currentTitle == String(op) {
        nrTaped = false

        nr2 = display.text!
        display.text! = String(String(nr1) + String(op))

    }

    for _ in op.0{

     self.calc.add(Int(nr1)!, secondNumber: Int(nr2)!)

    }



}

我在 for 循环中遇到错误.当我按 + 将数字加在一起时，我不知道如何使用我创建的字符串中的+"(例如)！

I get the error at the for loop. I don't know how to use the "+" (for example) from the String I created, when I press the + to add the numbers together!

推荐答案

错误很容易解决，需要访问String的CharacterView:

The error is easily solved, you need to access the String's CharacterView:

for _ in op.0.characters {

       self.calc.add(Int(nr1)!, secondNumber: Int(nr2)!)

}

注意:正如上面的另一位评论者所查询的那样，我不确定您为什么要迭代始终是单个且可预测的字符，但我想这可能只是示例代码.

Note: As another commenter has queried above, I'm not sure why you'd want to iterate over what will always be a single and predictable character but I guess this might just be example code.

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