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我做了一个自定义UIViewController调用ViewControllerA并希望能够使用它所以我做了一个如下所示的UIViewControllerRepresentable调用 ，但问题是当我在我的 SwiftUI 视图中调用并传递一个值时，说in是，我是不知道为什么。ViewControllerARepresentableViewControllerARepresentablestringToUpdateTextViewViewControllerAhtmlTextView(UITextView)ViewControllerAnil

ViewControllerARepresentable(stringToUpdateTextView: "<html>Send some Html Text as string here</html>")

ViewControllerARepresentable

public struct ViewControllerARepresentable: UIViewControllerRepresentable {
  var stringToUpdateTextView: String

  public func makeUIViewController(context: Context) -> ViewControllerA {
    let viewcontrollerA = ViewControllerA(testString: testingString)

    return viewcontrollerA
  }

  public func updateUIViewController(_ uiViewController: ViewControllerA, context: Context) {}
}

视图控制器A

open class ViewControllerA: UIViewController {

  public var stringToUpdateTextView: String

  override open func viewDidLoad() {
    super.viewDidLoad()

htmlTextView.text = stringToUpdateTextView
  }

  @IBOutlet weak var htmlTextView: UITextView!

  public init(testString: String) {
    self.testString = testString
    super.init(nibName: nil, bundle: nil)
  }

  required public init?(coder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
}

在说 htmlTextView.text 为 nil 时发生崩溃， htmlTextView.text = stringToUpdateTextView即使它是一个 IBOutlet。如果在 viewDidAppear 或 viewDidLoad 中调用，对 htmlTextView 所做的任何更改（如背景颜色等）也会导致崩溃

4

1 回答 1

4

在 中实例化视图控制器时makeUIViewController，出口尚未初始化。

以下代码从情节提要加载您的视图控制器，并更新以下属性updateUIViewController：

ViewController.swift

import UIKit
import SwiftUI

class ViewController: UIViewController {

  @IBOutlet weak var htmlTextView: UITextView!

  override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
  }

}

struct ViewControllerWrapper: UIViewControllerRepresentable {
  typealias UIViewControllerType = ViewController

  @Binding var text: String

  func makeUIViewController(context: Context) -> ViewController {
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    guard let viewController =  storyboard.instantiateViewController(
      identifier: "ViewController") as? ViewController else {
        fatalError("Cannot load from storyboard")
    }
    return viewController
  }

  func updateUIViewController(_ uiViewController: ViewController, context: Context) {
    uiViewController.htmlTextView.text = text
  }

}


struct ViewControllerPreview: PreviewProvider {
  static var previews: some View {
    ViewControllerWrapper(text: .constant("hello world!"))
  }
}

SwiftUIView.swift

struct SwiftUIView: View {
  @State var text = "Text"
  var body: some View {
    HStack {
      TextField("Text:", text: $text)
      ViewControllerWrapper(text: $text)
    }
  }
}
于 2020-06-17T07:55:10.787 回答