将 UITextView 属性字符串保存到 SwiftUI 中的文件

问题描述

我需要在 NSMutableAttributedString 中使用属性字符串 (SwiftUI) 来制作一个简单的富文本编辑器，而且您可能已经知道，SwiftUI 本身不支持属性字符串。因此，我不得不使用 UITextView 包装器处理旧的 UIViewRepresentable。

现在，我的应用程序是基于文档的应用程序，每当我尝试保存文件时，就会出现一些奇怪的问题：

第一个问题：当我运行应用程序并打开文件并开始输入时，文件的初始内容被删除。

第二个问题：每当我写文本并点击后退箭头保存文件时，它永远不会更新。所有文档仍具有相同的初始内容。

文档处理代码是您创建新的基于 SwiftUI 文档的应用程序时附带的默认代码，但是，我将编码从纯文本更改为 NSMutableAttributedString。（我还创建了一个名为 .mxt 而不是 .txt 的文档扩展名）

文档处理文件MyextDocument.swift：

import SwiftUI
import UniformTypeIdentifiers

extension UTType {
    static var MyextDocument = UTType(exportedAs: "com.example.Myext.mxt")
}

struct MyextDocument: FileDocument {
    var text: NSMutableAttributedString

    init(text: NSMutableAttributedString = NSMutableAttributedString()) {
        self.text = text
    }

    static var readableContentTypes: [UTType] { [.MyextDocument] }
    
    init(configuration: ReadConfiguration) throws {
        guard let data = configuration.file.regularFileContents,let string = try? NSMutableAttributedString(data: data,options: [NSMutableAttributedString.DocumentReadingOptionKey.documentType : NSMutableAttributedString.DocumentType.rtf],documentAttributes: nil)
        else {
            throw CocoaError(.fileReadCorruptFile)
        }
        text = string
    }
    
    func fileWrapper(configuration: WriteConfiguration) throws -> FileWrapper {
        let data = (try? text.data(from: NSMakeRange(0,text.length),documentAttributes: [.documentType: NSMutableAttributedString.DocumentType.rtf]))!
        return .init(regularFileWithContents: data)
    }
}

UIViewRepresentable 包装文件 iOSEditorTextView.swift：

import Combine
import SwiftUI
import UIKit

struct iOSEditorTextView: UIViewRepresentable {
    //@Binding var text: String
    @Binding var document: NSMutableAttributedString
    var isEditable: Bool = true
    var font: UIFont?    = .systemFont(ofSize: 14,weight: .regular)
    
    var onEditingChanged: () -> Void       = {}
    var onCommit        : () -> Void       = {}
    var onTextChange    : (String) -> Void = { _ in }
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    func makeUIView(context: Context) -> CustomTextView {
        let textView = CustomTextView(
            text: document,isEditable: isEditable,font: font
        )
        textView.delegate = context.coordinator
        
        return textView
    }
    
    func updateUIView(_ uiView: CustomTextView,context: Context) {
        uiView.text = document
        uiView.selectedRanges = context.coordinator.selectedRanges
    }
}

// MARK: - Preview

#if DEBUG

struct iOSEditorTextView_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            iOSEditorTextView(
                document: .constant(NSMutableAttributedString()),isEditable: true,font: .systemFont(ofSize: 14,weight: .regular)
            )
            .environment(\.colorScheme,.dark)
            .previewdisplayName("Dark Mode")
            
            iOSEditorTextView(
                document: .constant(NSMutableAttributedString()),isEditable: false
            )
            .environment(\.colorScheme,.light)
            .previewdisplayName("Light Mode")
        }
    }
}

#endif

// MARK: - Coordinator

extension iOSEditorTextView {
    
    class Coordinator: NSObject,UITextViewDelegate {
        var parent: iOSEditorTextView
        var selectedRanges: [NSValue] = []
        
        init(_ parent: iOSEditorTextView) {
            self.parent = parent
        }
        
        func textViewDidBeginEditing(_ textView: UITextView) {
            self.parent.document = textView.attributedText as! NSMutableAttributedString
            self.parent.onEditingChanged()
        }
        
        func textViewDidChange(_ textView: UITextView) {
            self.parent.document = textView.attributedText as! NSMutableAttributedString
            //self.selectedRanges = textView.selectedRange
        }

        func textViewDidEndEditing(_ textView: UITextView) {
            self.parent.document = textView.attributedText as! NSMutableAttributedString
            self.parent.onCommit()
        }
    }
}

// MARK: - CustomTextView

final class CustomTextView: UIView,UIGestureRecognizerDelegate,UITextViewDelegate {
    private var isEditable: Bool
    private var font: UIFont?
    
    weak var delegate: UITextViewDelegate?
    
    var text: NSMutableAttributedString {
        didSet {
            textView.attributedText = text
        }
    }
    
    var selectedRanges: [NSValue] = [] {
        didSet {
            guard selectedRanges.count > 0 else {
                return
            }
            
            //textView.selectedRanges = selectedRanges
        }
    }
        
    private lazy var textView: UITextView = {
        let textView                     = UITextView(frame: .zero)
        textView.delegate                = self.delegate
        textView.font                    = self.font
        textView.isEditable              = self.isEditable
        textView.textColor               = UIColor.label
        textView.textContainerInset      = UIEdgeInsets(top: 40,left: 0,bottom: 0,right: 0)
        textView.translatesAutoresizingMaskIntoConstraints = false
        
        return textView
    }()

    // Create paragraph styles
    let paragraphStyle = NSMutableParagraphStyle() // create paragraph style

    var attributes: [NSMutableAttributedString.Key: Any] = [
        .foregroundColor: UIColor.red,.font: UIFont(name: "Courier",size: 12)!
    ]
    
    // MARK: - Init
    init(text: NSMutableAttributedString,isEditable: Bool,font: UIFont?) {
        self.font       = font
        self.isEditable = isEditable
        self.text       = text
        
        super.init(frame: .zero)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    // MARK: - Life cycle
    
    override func draw(_ rect: CGRect) {
        super.draw(rect)
        
        setupTextView()
        
        // Set tap gesture
        let tap = UITapGestureRecognizer(target: self,action: #selector(didTapTextView(_:)))
        tap.delegate = self
        textView.addGestureRecognizer(tap)

        // create paragraph style
        self.paragraphStyle.headindent = 108
        
        // create attributed string
        let string = "Lorem ipsum dolor sit amet,consectetur adipiscing elit,sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident,sunt in culpa qui officia deserunt mollit anim id est laborum."
        
        // create attributes
        self.attributes = [
            .foregroundColor: UIColor.red,size: 12)!,.paragraphStyle: paragraphStyle,]

        // Create the Attributed String
        let myAttrString = NSMutableAttributedString(string: string,attributes: attributes)
        
        // Write it to the Text View
        textView.attributedText = myAttrString
    }
    
    // Show cursor and set it to position on tapping + Detect line
    @objc func didTapTextView(_ recognizer: UITapGestureRecognizer) {
        // Show cursor and set it to position on tapping
        if recognizer.state == .ended {
            textView.isEditable = true
            textView.becomeFirstResponder()
                        
            let location = recognizer.location(in: textView)
            if let position = textView.closestPosition(to: location) {
                let uiTextRange = textView.textRange(from: position,to: position)
                
                if let start = uiTextRange?.start,let end = uiTextRange?.end {
                    let loc = textView.offset(from: textView.beginningOfDocument,to: position)
                    let length = textView.offset(from: start,to: end)
                    
                    textView.selectedRange = NSMakeRange(loc,length)
                }
            }
            
        }
        
    }
        
    func setupTextView() {
        // Setup Text View delegate
        textView.delegate = self
        
        // Place the Text View on the view
        addSubview(textView)
        
        NSLayoutConstraint.activate([
            textView.topAnchor.constraint(equalTo: topAnchor),textView.trailingAnchor.constraint(equalTo: trailingAnchor),textView.leadingAnchor.constraint(equalTo: leadingAnchor),textView.bottomAnchor.constraint(equalTo: bottomAnchor)
        ])

    }
}

为了调用 UIViewRepresentable 包装器，我在 ContentView 中编写了以下代码：

iOSEditorTextView(
    document: $document.text,weight: .regular)
)

任何帮助将不胜感激。

解决方法

代码中有几个错误。

您设置了错误的委托。所以你的委托方法不起作用。给予自我代表，而不是自我。喜欢

func setupTextView() {
    // Setup Text View delegate
    textView.delegate = delegate

在委托中使用 NSMutableAttributedString。

func textViewDidBeginEditing(_ textView: UITextView) {
    self.parent.document = NSMutableAttributedString(attributedString: textView.attributedText)
    self.parent.onEditingChanged()
}

func textViewDidChange(_ textView: UITextView) {
    self.parent.document = NSMutableAttributedString(attributedString: textView.attributedText)
}

func textViewDidEndEditing(_ textView: UITextView) {
    self.parent.document = NSMutableAttributedString(attributedString: textView.attributedText)
    self.parent.onCommit()
}

Remove static text from override func draw(_ rect: CGRect) 此行覆盖现有文本。

override func draw(_ rect: CGRect) {
        super.draw(rect)
        
        setupTextView()
        
        // Set tap gesture
        let tap = UITapGestureRecognizer(target: self,action: #selector(didTapTextView(_:)))
        tap.delegate = self
        textView.addGestureRecognizer(tap)

        // create paragraph style
        self.paragraphStyle.headIndent = 108
        
        // create attributes
        self.attributes = [
            .foregroundColor: UIColor.red,.font: UIFont(name: "Courier",size: 12)!,.paragraphStyle: paragraphStyle,]
    }

注意：从绘制矩形中删除其他代码并使用 init 或 func awakeFromNib()

Raja 的所有问题都是正确的。我会做的另一件事是不将 vpc-1 值作为委托传递给您的 struct，因为您无法保证它的同一个实例稍后可用。改为将绑定传递给可变字符串要好得多。所以：

Coordinator

那么：

extension iOSEditorTextView {
    
    class Coordinator: NSObject,UITextViewDelegate {
        var documentBinding : Binding<NSMutableAttributedString>
        var selectedRanges: [NSValue] = []
        
        init(_ documentBinding: Binding<NSMutableAttributedString>) {
            self.documentBinding = documentBinding
        }
        
        func textViewDidBeginEditing(_ textView: UITextView) {
            documentBinding.wrappedValue = NSMutableAttributedString(attributedString: textView.attributedText)
        }
        
        func textViewDidChange(_ textView: UITextView) {
            documentBinding.wrappedValue = NSMutableAttributedString(attributedString: textView.attributedText)
            //self.selectedRanges = textView.selectedRange
        }

        func textViewDidEndEditing(_ textView: UITextView) {
            documentBinding.wrappedValue = NSMutableAttributedString(attributedString: textView.attributedText)
        }
    }
}

ios ios nsmutableattributedstring nsmutableattributedstring swift swift swift swift swiftui uikit uikit uikit