UIPickerView 在 vi​​ewWillAppear if 语句中不会改变颜色

Question

我正在制作一个应用程序，其中有 4 个选项卡，最后一个选项卡用于更改为暗模式（更改标签颜色、背景颜色、键盘颜色和 pickerView 颜色）。 func 是我改变颜色的地方。一切正常，除了 pickerView 没有改变颜色，所以我需要帮助。

override func viewWillAppear(_ animated: Bool) {

    if UserDefaults.standard.integer(forKey: "dark") == 1{

        self.view.backgroundColor = UIColor.darkGray
        UITextField.appearance().keyboardAppearance = .dark
        textField.backgroundColor = UIColor.white
        textField.textColor = UIColor.black
        textField2.textColor = UIColor.black
        textField2.backgroundColor = UIColor.white
        label.textColor = UIColor.white
        label.textColor = UIColor.white
        labelIN1.textColor = UIColor.white

        func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
            let titleData = list[row]
            let myTitle = NSAttributedString(string: titleData, attributes: [NSForegroundColorAttributeName:UIColor.black])
            return myTitle
        }


    }else{

        self.view.backgroundColor = UIColor.white
        UITextField.appearance().keyboardAppearance = .light
        textField.backgroundColor = UIColor.white
        textField.textColor = UIColor.black
        textField2.textColor = UIColor.black
        textField2.backgroundColor = UIColor.white
        label.textColor = UIColor.black
        label.textColor = UIColor.black
        labelIN1.textColor = UIColor.black

        func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
            let titleData = list[row]
            let myTitle = NSAttributedString(string: titleData, attributes: [NSForegroundColorAttributeName:UIColor.white])
            return myTitle
        }

    }

}

Answer 1

你的代码sn-p中pickerView(_:attributedTitleForRow:forComponent:)委托被声明为viewWillAppear中的嵌套函数的问题，如果它的作用域应该超出，如下：

override func viewWillAppear(_ animated: Bool) {

        if UserDefaults.standard.integer(forKey: "dark") == 1{

            self.view.backgroundColor = UIColor.darkGray
            UITextField.appearance().keyboardAppearance = .dark
            textField.backgroundColor = UIColor.white
            textField.textColor = UIColor.black
            textField2.textColor = UIColor.black
            textField2.backgroundColor = UIColor.white
            label.textColor = UIColor.white
            label.textColor = UIColor.white
            labelIN1.textColor = UIColor.white

        }else{

            self.view.backgroundColor = UIColor.white
            UITextField.appearance().keyboardAppearance = .light
            textField.backgroundColor = UIColor.white
            textField.textColor = UIColor.black
            textField2.textColor = UIColor.black
            textField2.backgroundColor = UIColor.white
            label.textColor = UIColor.black
            label.textColor = UIColor.black
            labelIN1.textColor = UIColor.black

        }
    }

    func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {

        let titleData = list[row]

        if UserDefaults.standard.integer(forKey: "dark") == 1{

            let myTitle = NSAttributedString(string: titleData, attributes: [NSForegroundColorAttributeName:UIColor.white])
            return myTitle

        } else {

            let myTitle = NSAttributedString(string: titleData, attributes: [NSForegroundColorAttributeName:UIColor.black])
            return myTitle
        }
    }

另外，请务必实施：

• class ViewController: UIViewController, UIPickerViewDelegate { /*...*/ }
• pickerView.delegete = self

在你的代码中。

有关更多信息，您可能需要查看this answer。