pickerView在展开Optional时意外发现了nil

Question

我有以下代码。没有错误。应用程序崩溃。不确定我是否正确初始化。拜托，非常感谢任何帮助。

@IBOutlet weak var myCostPicker: UIPickerView!

var costCode = String()

override func viewDidLoad() {
    super.viewDidLoad()
    if let projectNum = projectNum {
        projectNumTitle.title = projectNum

    }

    updateLabels()
    myCostPicker.dataSource = self
    myCostPicker.delegate = self
    myCostPicker.showsSelectionIndicator = true
    self.view.backgroundColor = UIColor.blackColor()
}

let pickerData = ["Nothing", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q"]

let costCodeData = ["Nothing", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q"]

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

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

// MARK: - Picker Delegates
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String {
    return pickerData[row]
}

func pickerView(pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
    let titleData = pickerData[row]
    var myTitle = NSAttributedString(string: titleData, attributes: [NSFontAttributeName:UIFont(name: "Georgia", size: 15.0)!,NSForegroundColorAttributeName:UIColor.whiteColor()])
    return myTitle
}

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    myLabel.text = pickerData[row]
    costCode = costCodeData[row]
}

达到心理障碍。需要有人来讨厌我的头脑。赞赏。

Answer 1

如果我理解你的问题是正确的，似乎你在故事板或XIB中完成了选择器设置，但是选择器似乎没有填充pickerData数组中的数据。

我尝试了你的代码并且它的工作非常好，它可能是你可能没有对正确的视图控制器类进行IBOutlet的链接。另外，如果你使用的是storyboard / XIB方法，请尝试添加数据源和委托自.storyboard或.xib文件本身

OR

由于一些有趣的原因，pickerData可能会被刷新，你可以使用调试器检查它。

如果所有设置都正确完成，那么你也无法看到最终输出，那么有时当你创建一个新的cocoa touch类文件时，它们的创建不正确，所以你删除它们并重新创建它们（我知道真实的愚蠢，但它确实有效）