ios - SwiftUI 中自定义 UIViewRepresentable UITextView 的框架高度问题

问题描述

我正在通过 UIViewRepresentable 为 SwiftUI 构建自定义 UITextView。它旨在显示NSAttributedString和处理链接按下。NavigationView一切正常，但是当我在带有内联标题的 a 内显示此视图时，框架高度完全混乱。

import SwiftUI

struct AttributedText: UIViewRepresentable {
  class Coordinator: NSObject, UITextViewDelegate {
    var parent: AttributedText

    init(_ view: AttributedText) {
      parent = view
    }

    func textView(_ textView: UITextView, shouldInteractWith URL: URL, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool {
      parent.linkPressed(URL)
      return false
    }
  }

  let content: NSAttributedString
  @Binding var height: CGFloat
  var linkPressed: (URL) -> Void

  public func makeUIView(context: Context) -> UITextView {
    let textView = UITextView()
    textView.backgroundColor = .clear
    textView.isEditable = false
    textView.isUserInteractionEnabled = true
    textView.delegate = context.coordinator
    textView.isScrollEnabled = false
    textView.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
    textView.dataDetectorTypes = .link
    textView.textContainerInset = .zero
    textView.textContainer.lineFragmentPadding = 0
    return textView
  }

  public func updateUIView(_ view: UITextView, context: Context) {
    view.attributedText = content

    // Compute the desired height for the content
    let fixedWidth = view.frame.size.width
    let newSize = view.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat.greatestFiniteMagnitude))

    DispatchQueue.main.async {
      self.height = newSize.height
    }
  }

  func makeCoordinator() -> Coordinator {
    Coordinator(self)
  }
}


struct ContentView: View {

  private var text: NSAttributedString {
    NSAttributedString(string: "Eartheart is the principal settlement for the Gold Dwarves in East Rift and it is still the cultural and spiritual center for its people. Dwarves take on pilgrimages to behold the great holy city and take their trips from other countries and the deeps to reach their goal, it use to house great temples and shrines to all the Dwarven pantheon and dwarf heroes but after the great collapse much was lost.\n\nThe lords of their old homes relocated here as well the Deep Lords. The old ways of the Deep Lords are still the same as they use intermediaries and masking themselves to undermine the attempts of assassins or drow infiltrators. The Gold Dwarves outnumber every other race in the city and therefor have full control of the city and it's communities.")
  }

  @State private var height: CGFloat = .zero

  var body: some View {
    NavigationView {
      List {
        AttributedText(content: text, height: $height, linkPressed: { url in print(url) })
          .frame(height: height)

        Text("Hello world")
      }
      .listStyle(GroupedListStyle())
      .navigationBarTitle(Text("Content"), displayMode: .inline)
    }
  }
}

struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
    ContentView()
  }
}

运行此代码时，您会看到AttributedText单元格太小而无法容纳其内容。

当您从中删除displayMode: .inline参数时navigationBarTitle，它显示得很好。

但是，如果我添加另一行来显示高度值 ( Text("\(height)"))，它会再次中断。

也许这是某种通过状态更改的视图更新触发的竞争条件？值本身是正确的height，只是框架实际上并没有那么高。有解决方法吗？

使用ScrollViewwith a确实可以解决问题，但由于内容在真实应用程序中的显示方式VStack，我真的更喜欢使用 a 。List

标签： iosswiftui

解决方案

所以我有这个确切的问题。

解决方案并不漂亮，但我找到了一个有效的解决方案：

首先，您需要继承 UITextView 以便您可以将其内容大小传递回 SwiftIU：

public class UITextViewWithSize: UITextView {
    @Binding var size: CGSize
    
    public init(size: Binding<CGSize>) {
        self._size = size
        
        super.init(frame: .zero, textContainer: nil)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    public override func layoutSubviews() {
        super.layoutSubviews()
        self.size = sizeThatFits(.init(width: frame.width, height: 0))
    }
}

完成此操作后，您需要为您的自定义 UITextView 创建一个 UIViewRepresentable：

public struct HyperlinkTextView: UIViewRepresentable {
    public typealias UIViewType = UITextViewWithSize
    
    private var text: String
    private var font: UIFont?
    private var foreground: UIColor?
    @Binding private var size: CGSize
    
    public init(_ text: String, font: UIFont? = nil, foreground: UIColor? = nil, size: Binding<CGSize>) {
        self.text = text
        self.font = font
        self.foreground = foreground
        self._size = size
    }
    
    public func makeUIView(context: Context) -> UIViewType {
        
        let view = UITextViewWithSize(size: $size)
        
        view.isEditable = false
        view.dataDetectorTypes = .all
        view.isScrollEnabled = false
        view.text = text
        view.textContainer.lineBreakMode = .byTruncatingTail
        view.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
        view.setContentCompressionResistancePriority(.required, for: .vertical)
        view.textContainerInset = .zero
        
        if let font = font {
            view.font = font
        } else {
            view.font = UIFont.preferredFont(forTextStyle: .body)
        }
        
        if let foreground = foreground {
            view.textColor = foreground
        }
        
        view.sizeToFit()
        
        return view
    }
    
    public func updateUIView(_ uiView: UIViewType, context: Context) {
        uiView.text = text
        uiView.layoutSubviews()
    }
}

现在我们可以轻松访问视图的内容大小，我们可以使用它来强制视图适合该大小的容器。出于某种原因，仅在视图上使用 .frame 是行不通的。视图只是忽略了它给定的框架。但是当将它放入几何阅读器时，它似乎按预期增长。

GeometryReader { proxy in
    HyperlinkTextView(bio, size: $bioSize)
        .frame(maxWidth: proxy.frame(in: .local).width, maxHeight: .infinity)
}
.frame(height: bioSize.height)

ios - SwiftUI 中自定义 UIViewRepresentable UITextView 的框架高度问题

问题描述

解决方案

推荐阅读