TextField没有更新给我可选“”

Question

我试图在调用函数时让textfield更新其标签。 当我调用它时，我得到一个Optional“”的返回，文本字段变为空白。以下是我的代码..

func P18Switch() {

        if metricImperialSwitch?.selectedSegmentIndex == 0
        {
            measurementSwitch = 0
            CWLabel.text = "kg"; TWLabel.text = "kg"; CWaLabel.text = "cm"; TWaLabel.text = "cm"; CHLabel.text = "cm"; THLabel.text = "cm"


            if CWeight.text == "" {
                print("No go")
        } else {

//                 b = 0.453592
//                 c =  Double
//                 d = Double(CWeight.text!)

                c = d! * b

                CWeight.text = c as? String
                print(CWeight.text)
            }
        }

我早先宣布了b，c和d

Answer 1

不要将Double转换为String，而是执行此操作：

CWeight.text = String(c)