Ios Swift-UIToolbar，带完成按钮，用于UIPickerView在景观上消失

我制作了一个UIPickerView作为UITextField的输入，并实现了一个带有Done按钮的UIToolbar。它工作得很好，但当我在iPhone上切换到横向模式时，UIToolbar消失了。这是我的密码：

override func viewDidLoad() {
    super.viewDidLoad()

    thePicker.delegate = self

    let toolBar = UIToolbar()
    toolBar.barStyle = UIBarStyle.default

    toolBar.isTranslucent = true
    toolBar.tintColor = UIColor(red: 76/255, green: 100/255, blue: 217/255, alpha: 1)
    toolBar.sizeToFit()

    let doneButton = UIBarButtonItem(title: "Aceptar", style: UIBarButtonItemStyle.plain, target: self, action: #selector(doneClick))


    toolBar.setItems([doneButton], animated: false)
    toolBar.isUserInteractionEnabled = true

    testTextField.inputView = thePicker
    testTextField.inputAccessoryView = toolBar

}

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当我以编程方式添加UIPickerView并为PickerView添加UIToolBar时，遇到了相同的问题。只需为UIPickerView添加[.flexibleWidth、.flexibleHeight]

self.thePicker.autoresizingMask = [.flexibleWidth,.flexibleHeight]