SwiftUI inputAccesoryView 实现

Question

我正在尝试在 SwiftUI 中的 TextField 上实现 inputAccessoryView。目标是在键盘上方出现一个“完成”按钮，按下该按钮后即可摆脱键盘（即 resignFirstResponder()）。

我遇到了以下 Medium 文章，该文章声称完全按照我的要求实施此行为，但是，我正在努力使其正常工作。

包含要实现的方法的媒体链接。

我试图在一个空白的 XCode 项目中实现这个，我的代码编译，但是，TextField 永远不会出现，我无法触摸应该调出键盘的区域。如何正确实现此代码以获得所需的行为？

代码

    import Foundation
import UIKit
import SwiftUI

class TextFieldViewController
    : UIViewController {

    // our custom text field will report changes to the outside
    let text: Binding<String>?

    // if the toolbar (see below) is used (Done), the keyboard shall be dismissed
    // and optionally we execute a provided closure
    let onDismiss: (() -> Void)?

    init (
        text: Binding<String>
        , onDismiss: (() -> Void)?) {

        self.text = text
        self.onDismiss = onDismiss

        super.init(
            nibName: nil //"<XIB>"
            , bundle: nil //Bundle.main?
        )
    }

    required init?(coder: NSCoder) {
        self.text = nil
        self.onDismiss = nil

        super.init(coder: coder)
    }

    // helper function to encapsulate calling the "view" of UIViewController
    fileprivate func getTextField() -> UITextField? {
        return view as? UITextField
    }

    override func viewDidLoad() {
        let textField = self.getTextField()
        guard textField != nil else {
            return
        }

        // configure a toolbar with a Done button
        let toolbar = UIToolbar()
        toolbar.setItems([
                // just moves the Done item to the right
                UIBarButtonItem(
                    barButtonSystemItem: UIBarButtonItem.SystemItem.flexibleSpace
                    , target: nil
                    , action: nil
                )
                , UIBarButtonItem(
                    title: "Done"
                    , style: UIBarButtonItem.Style.done
                    , target: self
                    , action: #selector(self.onSet)
                )
            ]
            , animated: true
        )
        toolbar.barStyle = UIBarStyle.default
        toolbar.sizeToFit()
        textField?.inputAccessoryView = toolbar
    }

    @objc private func onSet() {
        let textField = self.getTextField()
        textField?.resignFirstResponder()

        self.text?.wrappedValue = textField?.text ?? ""
        self.onDismiss?()
    }

}

// The SwiftUI view, wrapping the UITextField
struct TextFieldView: View {

    var text: Binding<String>
    var onDismissKeyboard: (() -> Void)?

    var body: some View {
        TextFieldRepresentable(
            text: self.text
            , dismissKeyboardCallback: self.onDismissKeyboard
        )
    }
}

// The UIViewControllerRepresentable, feeding and controlling the UIViewController
struct TextFieldRepresentable
    : UIViewControllerRepresentable {

    // the callback
    let dismissKeyboardCallback: (() -> Void)?

    // created in the previous file/gist
    let viewController: TextFieldViewController

    init (
        text: Binding<String>
        , dismissKeyboardCallback: (() -> Void)?) {

        self.dismissKeyboardCallback = dismissKeyboardCallback
        self.viewController = TextFieldViewController(
            text: text
            , onDismiss: dismissKeyboardCallback
        )
    }

    // UIViewControllerRepresentable
    func makeUIViewController(context: Context) -> UIViewController {

        return viewController
    }

    // UIViewControllerRepresentable
    func updateUIViewController(_ viewController: UIViewController, context: Context) {
    }

}

struct ContentView : View {

    @State var email:String = ""

    var body: some View {

        HStack{
        Circle()
        TextFieldView(text: $email)
        Circle()
        }
    }
} 

Answer 1

这是一个带有自定义工具栏和输入文本绑定的演示，但通过排除关闭回调来简化（因为它对于方法演示并不重要），只是为了减少代码。希望它会有所帮助。

import SwiftUI
import UIKit
import Combine

struct CustomInputTextField : UIViewRepresentable {

    @Binding var text: String

    let textField = UITextField(frame: CGRect(x:0, y:0, width: 100, height: 32)) // just any

    func makeUIView(context: UIViewRepresentableContext<CustomInputTextField>) -> UITextField {
        return textField
    }

    func updateUIView(_ uiView: UITextField, context: UIViewRepresentableContext<CustomInputTextField>) {
        self.textField.text = text
    }

    func makeCoordinator() -> CustomInputTextField.Coordinator {
        let coordinator = Coordinator(self)

        // configure a toolbar with a Done button
        let toolbar = UIToolbar()
        toolbar.setItems([
            // just moves the Done item to the right
            UIBarButtonItem(
                barButtonSystemItem: UIBarButtonItem.SystemItem.flexibleSpace
                , target: nil
                , action: nil
            )
            , UIBarButtonItem(
                title: "Done"
                , style: UIBarButtonItem.Style.done
                , target: coordinator
                , action: #selector(coordinator.onSet)
            )
            ]
            , animated: true
        )
        toolbar.barStyle = UIBarStyle.default
        toolbar.sizeToFit()

        textField.inputAccessoryView = toolbar
        return coordinator
    }

    typealias UIViewType = UITextField

    class Coordinator: NSObject {
        let owner: CustomInputTextField
        private var subscriber: AnyCancellable

        init(_ owner: CustomInputTextField) {
            self.owner = owner
            subscriber = NotificationCenter.default.publisher(for: UITextField.textDidChangeNotification, object: owner.textField)
                .sink(receiveValue: { _ in
                    owner.$text.wrappedValue = owner.textField.text ?? ""
                })
        }

        @objc fileprivate func onSet() {
            owner.textField.resignFirstResponder()
        }

    }
}

struct DemoCustomKeyboardInput : View {

    @State var email:String = ""

    var body: some View {
        VStack{
            CustomInputTextField(text: $email).border(Color.black)
                .padding(.horizontal)
                .frame(maxHeight: 32)
            Divider()
            Text("Entered text: \(email)")
        }
    }
}

struct DemoCustomKeyboardInput_Previews: PreviewProvider {
    static var previews: some View {
        DemoCustomKeyboardInput()
    }
}