我在评论中提出了问题。前3行一定要弱吗?以及如何使var工资和var工时等于文本框。
@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)
}
如何接受UITextField的Double输入并赋值到变量?
类似这样的东西:
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.
}
//这需要弱吗
如果有问题的子视图(在本例中为UITextField)是在情节提要中定义的,则不会:它已经被其父视图强引用,因此您的出口引用不需要强引用它来防止解除分配。