有没有办法告诉 iOS 更新视图控制器中的键盘外观？答案

【问题标题】：Is there a way to tell iOS to update the keyboard appearance within a view controller?有没有办法告诉 iOS 更新视图控制器中的键盘外观？
【发布时间】：2019-05-03 10:51:54
【问题描述】：

我想在ViewController 中更新UIKeyboardAppearance。我的意思是说，VC 加载了UIKeyboardAppearance.default。如果我按下一个按钮，我希望键盘更新为.dark，并让键盘现在显示在与.dark 相同的VC 中。

据我所知，iOS 在加载 VC 时会检查 UIKeyboardAppearance 的值，并且在再次加载 VC 之前不会再次检查。即使您更改 UIKeyboardAppearance 的值并隐藏/显示键盘。

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

// creating a simple text box, and making the placeholder text the value of the keyboardAppearance
        myTextBox.backgroundColor = UIColor.lightGray
        myTextBox.frame = CGRect(x: 30, y: 200, width: 300, height: 50)
        view.addSubview(myTextBox)
        UITextField.appearance().keyboardAppearance = .dark
        myTextBox.becomeFirstResponder()
        myTextBox.placeholder = "Keybaoard Appearance is: \(UITextField.appearance().keyboardAppearance.rawValue)"

// a simple button to toggle the keyboardAppearance
        toggleButton.frame = CGRect(x: 30, y: 300, width: 300, height: 50)
        toggleButton.setTitle("Toggle Keyboard", for: .normal)
        toggleButton.backgroundColor = UIColor.red
        toggleButton.addTarget(self, action: #selector(toggleButtonFunction), for: .touchUpInside)
        view.addSubview(toggleButton)

    }

// toggles the keyboardAppearance. Hides the keyboard, and a second later shows it again.
    @objc func toggleButtonFunction() {
        if UITextField.appearance().keyboardAppearance == .dark {
            UITextField.appearance().keyboardAppearance = .default
        }
        else {
            UITextField.appearance().keyboardAppearance = .dark
        }
        myTextBox.resignFirstResponder()
        DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(1), execute: {
            self.myTextBox.becomeFirstResponder()
            self.myTextBox.placeholder = "Keybaoard Appearance is: \(UITextField.appearance().keyboardAppearance.rawValue)"

            })
    }

    let myTextBox = UITextField()
    let toggleButton = UIButton()
}

我希望在更改 UIKeyboardAppearance 并隐藏/显示键盘后，它会以新外观（.dark 或 .default）显示，但它会继续以相同的外观显示，直到再次加载 VC .您可以看到 UIKeyboardAppearance 的值发生了变化，但 iOS 似乎在 VC 再次加载之前不会检查该更新。

有没有办法在 VC 中强制重新检查？

感谢您的帮助！

【问题讨论】：

标签： ios swift uiviewcontroller uikeyboard

【解决方案1】：

您可以递归地更改屏幕上所有文本字段的键盘外观（allSubviewsOf(type:) 扩展名来自 this great answer by Mohammad Sadiq）：

func changeTextFieldKeyboardAppearance() {
    UITextField.appearance().keyboardAppearance = .dark

    let textFields = view.allSubviewsOf(type: UITextField.self)

    let firstResponder = textFields.first { $0.isFirstResponder }

    firstResponder?.resignFirstResponder()

    textFields.forEach { $0.keyboardAppearance = .dark }

    firstResponder?.becomeFirstResponder()
}

[...]

extension UIView {
    func allSubviewsOf<T: UIView>(type: T.Type) -> [T] {
        var all = [T]()

        func getSubview(view: UIView) {
            if let aView = view as? T {
                all.append(aView)
            }

            guard !view.subviews.isEmpty else {
                return
            }

            view.subviews.forEach{ getSubview(view: $0) }
        }

        getSubview(view: self)

        return all
    }
}

如果您的视图控制器嵌入在 UITabBarController 中，您可以通过更改其 selectedIndex 并立即将其更改回原始索引来触发更新：

guard let tabBarController = tabBarController else {
    return
}

let selectedIndex = tabBarController.selectedIndex

UITextField.appearance().keyboardAppearance = .dark

tabBarController.selectedIndex = selectedIndex == 1 ? 0 : 1
tabBarController.selectedIndex = selectedIndex

【讨论】：

【解决方案2】：

感谢 Tamás 的回答！

它引导我找到我需要的东西。

如果您更改 UITextField 的键盘外观，看起来就像

UITextField.appearance().keyboardAppearance = .dark

系统仅检查 VC 负载。如果您为每个文本字段更改它

myTextBox.keyboardAppearance = .dark

系统将检查每次 firstResponder 更改并加载正确的键盘。

再次感谢 Tamás！

【讨论】：