ios - 在 swift 中将 UIPickerView 设置为 UITextField 的输入时出错

Question

我是 swift 编程的新手，我想将 UIPickerView 设置为 UITextField 的输入。这是我的代码:

import UIKit

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

    @IBOutlet var  selectTransportCompany: UITextField!
    var data = ["DHL Express", "Fed Ex", "TNT", "Express Mail"]
    var picker = UIPickerView()

    override func viewDidLoad() {
        super.viewDidLoad()
        picker.delegate = self
        picker.dataSource = self
        selectTransportCompany.inputView = picker
    }

    func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int{
        return 1
    }

    func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int{
        return data.count
    }

    func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        selectTransportCompany.text = data[row]

    }

    func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return data[row]
    }


}

但是，当我运行这段代码时，我得到一个错误提示

Thread 1 : EXC_BAD_INSTRUCTION

进入调试器，我得到这个:

fatal error: unexpectedly found nil while unwrapping an Optional value

谁能知道是什么问题，我关注了this tutorial也是。

Answer 1

您只需将您的 View Controller 文本字段导出连接到您的 Storyboard selectTransportCompany 文本字段。