ios - 如何接受来自 UITextField 的 Double 输入，并将值赋给变量？

Question

我在评论中提出了我的问题。前三行必须弱吗？以及如何让 var wage 和 var hours 等于文本框。

@IBOutlet var wageIn: UITextField! //does this need to be weak
@IBOutlet var hoursIn: UITextField!//does this need to be weak
@IBOutlet var payOut: UILabel! //does this need to be weak
@IBAction func goButt(sender: AnyObject) {

    var wage: Double = //wageIn
    var hours: Double = //hoursIn
    var prePay: Double = wage*hours


    let tax: Double = fitwCalc(prePay)  
    payOut.text = String(prePay - tax)
}

Answer 1

How to accept input of a Double from a UITextField, and assign value to variable?

像这样:

var myDoubleVariable:Double

if let text = textField.text {
    myDoubleVariable = Double(text) ?? 0.0
    // (Text may not represent valid double value e.g. the string "Hellow world!"); in 
    // which case the initialization will fail (return nil).
    // The code above falls back to "0.0" in such case.
}

//does this need to be weak

如果有问题的 subview (在本例中为 UITextField)是在 Storyboard 中定义的，则不是:它已经被其父 View 强引用，因此您的 outlet 引用不需要强引用它来防止释放。