swift3 - 可以更改 UIPickerView 的全局文本颜色吗？

Question

我的两个 pickerView 遇到问题。我想知道是否可以更改 AppDelegate 文件中 pickerViews 的全局文本颜色？

我知道可以做一些事情，例如:

UIPickerView.appearance().backgroundColor = color6
UIPickerView.appearance().tintColor = color4

如果我需要在每个 pickerView 中手动将其写入代码中。应该将其编码为哪种类型的 pickerView，titleForRow？

Answer 1

尝试使用以下类。我已经对 UIPickerView 进行了子类化并在其中指定了颜色。这工作正常。当您设置项目时。它将把委托(delegate)和数据源设置为 self，并为您完成这项工作。

   import UIKit
    class CustomUIPickerView: UIPickerView{
        let textColor: UIColor = .white
        let backGroundColor: UIColor = .blue
        let _tintColor: UIColor = .white
        var items: [String]?{
            didSet{
                self.delegate = self
                self.dataSource = self
                self.reloadAllComponents()
            }
        }
        override init(frame: CGRect) {
            super.init(frame: frame)
           commonInit()
        }

        func commonInit(){
            self.backgroundColor = backGroundColor
            self.tintColor = _tintColor
        }

        required init?(coder aDecoder: NSCoder) {
            super.init(coder: aDecoder)
            commonInit()
        }
    }
    extension CustomUIPickerView: UIPickerViewDataSource{
        func numberOfComponents(in pickerView: UIPickerView) -> Int {
            return 1
        }

        func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
            return self.items?.count ?? 0
        }

    }
    extension CustomUIPickerView: UIPickerViewDelegate{
        func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
            let string = self.items?[row] ?? ""
            return NSAttributedString(string: string, attributes: [NSAttributedStringKey.foregroundColor: textColor])
        }
    }

但是，如果您想在 View Controller 中处理委托(delegate)和数据源，那么您可以利用扩展，具体方法如下:

extension String{
    func stringForPickerView() -> NSAttributedString{
        let color: UIColor = .white
        return NSAttributedString(string: self, attributes: [NSAttributedStringKey.foregroundColor: color])
    }
}

然后在你的 ViewController 中:

extension ViewController: UIPickerViewDelegate{
    func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
        return self.items[row].stringForPickerView() // from Extension
    }
}