UITextField - 无法解开 Optional.None [英] UITextField - Can't unwrap Optional.None

问题描述

我刚刚开始使用 Swift 进行编码，并尝试构建一个计算器.当我启动模拟器并单击计算器的按钮1"时，它会调用 Tap0 函数.我遇到了以下问题:Can't unwrap Optional.None.

I just started coding with Swift and I try to build a calculator. When I launch the simulator and I click the button '1' of the calculator it calls Tap0 function. I encountered the following issue: Can't unwrap Optional.None.

import UIKit

class ViewController: UIViewController {
  @IBOutlet var display:UITextField

  override func viewDidLoad() {
    super.viewDidLoad()
  }

  override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
  }

  @IBAction func Tap0(sender:AnyObject){AddNumber("0")}

  func AddNumber(x:String){
    self.display.text="" //ERROR (Can't unwrap Optional.None)
    println(self.display.text)
  }
}

我该如何解决?

推荐答案

按照 rdelmar 的建议，为了解决错误，将显示连接到 StoryBoard 中的 UITextField:

As what rdelmar suggested, to solve the error, connect display to the UITextField in StoryBoard:

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