I need to work with attributed strings (NSMutableAttributedString) in SwiftUI to make a simple rich-text editor, and as you might already know, attributed strings are not natively supported in SwiftUI. So I had to work with the old UITextView using a UIViewRepresentable wrapper.
Now, my app is a document-based app, and whenever I try to save the files, some strange problems happens:
First Problem: When I run the app and open a file, and start typing, the initial contents of the file are erased.
Second Problem: Whenever I write text and hit the back arrow to save file, it's never updated. All documents still have the same initial content.
The code for document processing is the default code that came when you create a new SwiftUI document-based app, but, I changed the encoding from plain text to NSMutableAttributedString. (I also created a document extension called .mxt instead of .txt)
Document processing file 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 wrapper file 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,
.font: UIFont(name: "Courier", 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)
])
}
}
And to call the UIViewRepresentable wrapper, I wrote the following code in the ContentView:
iOSEditorTextView(
document: $document.text,
isEditable: true,
font: .systemFont(ofSize: 14, weight: .regular)
)
Any help will be appreciated.
question from:
https://stackoverflow.com/questions/65839021/save-a-uitextview-attributed-string-to-file-in-swiftui 
