ios – 以编程方式创建和显示UIPickerView

我试图以编程方式创建UIPickerView并将其显示为文本字段的firstResponder,但是,选择器视图未显示. textField连接到接口构建器中的对象,但是正在以编程方式创建pickerView.

class View: UIViewController {
    @IBOutlet var picker : UIPickerView = UIPickerView.alloc()
    @IBOutlet var textField : UITextField = nil
    override func viewDidLoad() {
        super.viewDidLoad()
        picker = UIPickerView()
        picker.delegate = self
        picker.datasource = self
        picker.BACkgroundColor = UIColor.blackColor()
        textField.inputView = picker
    }
}
extension View: UIPickerViewDatasource {

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

    func pickerView(pickerView: UIPickerView!,numberOfRowsInComponent component: int) -> Int {
        return 5
    }
}

extension View: UIPickerViewDelegate {

    func pickerView(pickerView: UIPickerView!,@R_696_10283@eForRow row: Int,forComponent component: int) -> String!
    {
        return "Text"
    }
}

为什么我在运行应用程序时看不到这个pickerView？

编辑：在扩展中添加断点不会停止程序,它们不会被调用.

self.textField.inputView = picker