Swift 文本字段和值验证

Question

这看起来很简单，但我无法通过网络搜索找到解决方案。我有以下需要验证的变量。如果验证不正确，那么我希望应用程序停止并返回 Storyboard。

  let mortgageTerm = Double(mortgageTermLabel.text!)
  let name 
  let mtgCashback = Double(casbackRecieved.text!)
  let mtgBalance = Double(mortgageBalance.text!)
  let rate = Double(currentRate.text!)

• 抵押期限需要大于6且小于或等于60

• 房贷余额需大于10000

• 比率应该大于1但小于10

并且必须为控件选择一个值 @IBOutlet weak var lenderName: UITextField! - 我是一个客户选择器，为用户提供选择选项。

Answer 1

你可以使用guard let这是一个例子

guard let mortgage = Double(mortgageTermLabel.text!) , mortgage > 6 && mortgage <= 60 else {return}

此外，您还可以通过这种方式在返回前显示友好的提示信息

guard let mortgage = Double(mortgageTermLabel.text!) , mortgage > 6 && mortgage <= 60 else {
    let alert = UIAlertController(title: "blah", message: "blah blah", preferredStyle: .alert)
    alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))

    self.present(alert, animated: true, completion: nil)
    return
}

guard let balance = Double(mortgageBalance.text!) , balance > 10000 else {
    let alert = UIAlertController(title: "blah", message: "blah blah", preferredStyle: .alert)
    alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))

    self.present(alert, animated: true, completion: nil)
    return
}

guard let date = YourDate , date < Date() else {
    let alert = UIAlertController(title: "blah", message: "blah blah", preferredStyle: .alert)
    alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))

    self.present(alert, animated: true, completion: nil)
    return
}