ios - 添加 UIPickerView 作为 subview ，很奇怪

Question

最近我需要一个解决方案来显示一个类似于 present 的 pickerView，用于为某些属性(如配置文件)选择数据。我所做的是1、创建一个空项目2，创建一个将用作 subview 的AViewController。我在该 View 中添加了一个 pickerView 和一个导航栏，并将 View 的高度调整到 260 左右。3、在那个AViewController的类中写代码。

class APickerViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

@IBOutlet weak var pickerView:UIPickerView!
let dataList = [["a","b","c","d"]]

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
    //pickerView.dataSource = self
    //pickerView.delegate = self
}

func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return dataList.count
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return dataList[component].count
}

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

4、在Main ViewController中编写代码，将AViewController的View添加为子view。

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    let pickerViewController = storyboard?.instantiateViewController(withIdentifier: String(APickerViewController.self)) as! APickerViewController

    self.view.addSubview(pickerViewController.view)
    self.view.bringSubview(toFront: pickerViewController.view)

    pickerViewController.view.frame = CGRect(x: 0, y: self.view.frame.height - 300, width: self.view.frame.width, height: 300)



}

还有一个问题，实际上我不太确定其中的区别。答:

let pickerViewController = storyboard?.instantiateViewController(withIdentifier: String(APickerViewController.self)) as! APickerViewController

乙:

let pickerViewController = APickerViewController()

A 和 B 有什么不同？如果我通过 Interface Builder 做一些 @IBOutlet 设置会受到影响还是什么？

5，去……感到奇怪……

函数

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return dataList[component].count
}

有时会被多次调用，有时不会被调用。

并且数据没有显示在 pickerView 中，有时只显示第 1,2 行而没有其他行，如果我向上或向下滑动，那些 1,2 行数据就会消失。

如果有人有使用 pickerView 作为选项弹出窗口的更好解决方案？

帮助。

谢谢

Answer 1

class EditViewController: UIViewController,UITextFieldDelegate,UIPickerViewDelegate{ 

var picker : UIPickerView = UIPickerView()
 var toolBar : UIToolbar = UIToolbar() 
 @IBOutlet var txtFieldState: UITextField!
 var stateArray = ["Andaman & Nicobar Island","Andhra Pradesh","Arunachal Pradesh","Assam","Bihar","Chandigarh","Chhattisgarh","Dadra & Nagar"]
  override func viewDidLoad() {
        super.viewDidLoad()
txtFieldState.delegate = self
}
func textFieldDidBeginEditing(textField: UITextField) {
if textField == txtFieldState{ 
            txtFieldState.inputView = picker
            txtFieldState.inputAccessoryView = toolBar
            self.configurePicker()
}
    }

func configurePicker()
    {
        picker.alpha = 1.0
        picker.backgroundColor = UIColor(red:241/255.0, green:241/255.0, blue:241/255.0, alpha: 1.0)
        picker.showsSelectionIndicator = true
        picker.delegate = self
        picker.selectedRowInComponent(0)
        let screenRect = self.view.frame
        let pickerSize = picker.sizeThatFits(CGSizeZero)

        let x = screenRect.origin.x + (screenRect.size.width / 2) - (pickerSize.width / 2)

        let pickerRect = CGRectMake(x,
                                    screenRect.origin.y + (screenRect.size.height) - (pickerSize.height),
                                    pickerSize.width,
                                    pickerSize.height)

        picker.frame = pickerRect

        let toolbarSize = toolBar.sizeThatFits(CGSizeZero)
        toolBar.frame = CGRectMake(x,pickerRect.origin.y, // right under the picker
            pickerSize.width, // make them the same width
            toolbarSize.height)

    }
    func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int){
        dropState = row
        txtFieldState.text = "\(stateArray[row])"
    }

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

        return stateArray.count
    }

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