iphone - pickerView 显示为问号而不是数据？

Question

我正在尝试向我的 iPhone 应用程序添加一个 pickerview，但它没有显示数组中的字符串，而是显示了问号。有谁知道为什么？在过去的一个小时里，我一直在努力解决这个问题……这是我的包含 pickerview 的 Controller 代码:

class NewIssueViewController: UIViewController, UIPickerViewDelegate {

    var componentArr = ["component1","component2","component3","component4"]

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.


    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func CancelPressed(sender: AnyObject) {
        self.dismissViewControllerAnimated(true, completion: nil)
    }

    @IBAction func AddPressed(sender: AnyObject) {
        self.dismissViewControllerAnimated(true, completion: nil)
    }

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

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

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

Answer 1

您设置了选择器 View 的数据源，但没有设置它的委托(delegate)。

因此 pickerView:titleForRow: 永远不会被调用。