Question
I've implemented a NSTextView SwiftUI-wrapper (following this great example). There are several of these NSTextViews on my view. In the app's menu, there is a button that should change the currently focused NSTextView's content, e.g:
Is there a way to determine which NSTextView is currently focused? In my current solution, I resorted to storing the NSTextView in a global view model's variable by passing the NSTextView when its "becomeFirstResponder" is called.
However, I'm afraid this solution could either lead to retain cycles or to the NSTextView stored in the view model becoming nil. Is there a cleaner way of doing this? Any help is appreciated!
Current solution/Code
NSTextView
struct TextArea: NSViewRepresentable {
// Source : https://stackoverflow.com/a/63761738/2624880
@Binding var text: NSAttributedString
@Binding var selectedRange: NSRange
@Binding var isFirstResponder: Bool
func makeNSView(context: Context) -> NSScrollView {
context.coordinator.createTextViewStack()
}
func updateNSView(_ nsView: NSScrollView, context: Context) {
if let textArea = nsView.documentView as? NSTextView {
textArea.textStorage?.setAttributedString(self.text)
if !(self.selectedRange.location == textArea.selectedRange().location && self.selectedRange.length == textArea.selectedRange().length) {
textArea.setSelectedRange(self.selectedRange)
}
// Set focus (SwiftUI AppKit)
if isFirstResponder {
nsView.becomeFirstResponder()
DispatchQueue.main.async {
if ViewModel.shared.focusedTextView != textArea {
ViewModel.shared.focusedTextView = textArea
}
}
} else {
nsView.resignFirstResponder()
}
}
}
func makeCoordinator() -> Coordinator {
Coordinator(text: $text, selectedRange: $selectedRange, isFirstResponder: $isFirstResponder)
}
class Coordinator: NSObject, NSTextViewDelegate {
var text: Binding<NSAttributedString>
var selectedRange: Binding<NSRange>
var isFirstResponder: Binding<Bool>
init(text: Binding<NSAttributedString>,
selectedRange: Binding<NSRange>,
isFirstResponder: Binding<Bool>) {
self.text = text
self.selectedRange = selectedRange
self.isFirstResponder = isFirstResponder
}
func textView(_ textView: NSTextView, shouldChangeTextIn range: NSRange, replacementNSAttributedString text: NSAttributedString?) -> Bool {
defer {
self.text.wrappedValue = textView.attributedString()
self.selectedRange.wrappedValue = textView.selectedRange()
}
return true
}
fileprivate lazy var textStorage = NSTextStorage()
fileprivate lazy var layoutManager = NSLayoutManager()
fileprivate lazy var textContainer = NSTextContainer()
fileprivate lazy var textView: NSTextViewWithFocusHandler = NSTextViewWithFocusHandler(frame: CGRect(), textContainer: textContainer)
fileprivate lazy var scrollview = NSScrollView()
func textDidChange(_ notification: Notification) {
guard let textView = notification.object as? NSTextView else { return }
self.text.wrappedValue = NSAttributedString(attributedString: textView.attributedString())
self.selectedRange.wrappedValue = textView.selectedRange()
}
func textViewDidChangeSelection(_ notification: Notification) {
guard let textView = notification.object as? NSTextView else { return }
DispatchQueue.main.async {
if !(self.selectedRange.wrappedValue.location == textView.selectedRange().location && self.selectedRange.wrappedValue.length == textView.selectedRange().length) {
self.selectedRange.wrappedValue = textView.selectedRange()
}
}
}
func textDidBeginEditing(_ notification: Notification) {
DispatchQueue.main.async {
self.isFirstResponder.wrappedValue = true
}
}
func textDidEndEditing(_ notification: Notification) {
DispatchQueue.main.async {
self.isFirstResponder.wrappedValue = false
}
}
func createTextViewStack() -> NSScrollView {
let contentSize = scrollview.contentSize
textContainer.containerSize = CGSize(width: contentSize.width, height: CGFloat.greatestFiniteMagnitude)
textContainer.widthTracksTextView = true
textView.minSize = CGSize(width: 0, height: 0)
textView.maxSize = CGSize(width: CGFloat.greatestFiniteMagnitude, height: CGFloat.greatestFiniteMagnitude)
textView.isVerticallyResizable = true
textView.frame = CGRect(x: 0, y: 0, width: contentSize.width, height: contentSize.height)
textView.autoresizingMask = [.width]
textView.delegate = self
scrollview.borderType = .noBorder
scrollview.hasVerticalScroller = true
scrollview.documentView = textView
scrollview.layer?.cornerRadius = 10
scrollview.drawsBackground = false
textStorage.addLayoutManager(layoutManager)
layoutManager.addTextContainer(textContainer)
return scrollview
}
}
}
class NSTextViewWithFocusHandler: NSTextView {
override func becomeFirstResponder() -> Bool {
// ⚠️ Set self as currently focused TextView (AppKit SwiftUI)
ViewModel.shared.focusedTextView = self
return super.becomeFirstResponder()
}
}
ViewModel
class ViewModel: ObservableObject {
static let shared = ViewModel()
@Published var attributedTextQuestion: NSAttributedString = NSAttributedString(string: "Initial value question")
@Published var attributedTextAnswer: NSAttributedString = NSAttributedString(string: "Initial value answer")
@Published var selectedRangeQuestion: NSRange = NSRange()
@Published var selectedRangeAnswer: NSRange = NSRange()
@Published var questionFocused: Bool = false // Only works in direction SwiftUI AppKit
@Published var answerFocused: Bool = false // (dito)
weak var focusedTextView: NSTextView? {didSet{
DispatchQueue.main.async {
self.menuItemEnabled = self.focusedTextView != nil
}
}}
@Published var menuItemEnabled: Bool = false
}
ContentView
struct ContentView: View {
@ObservedObject var model: ViewModel
var body: some View {
VStack {
Text("Question")
TextArea(text: $model.attributedTextQuestion,
selectedRange: $model.selectedRangeQuestion,
isFirstResponder: $model.questionFocused)
Text("Answer")
TextArea(text: $model.attributedTextAnswer,
selectedRange: $model.selectedRangeAnswer,
isFirstResponder: $model.answerFocused)
}
.padding()
}
}
App
@main
struct TextViewMacOSSOFrageApp: App {
@ObservedObject var model: ViewModel = ViewModel.shared
var body: some Scene {
WindowGroup {
ContentView(model: model)
}.commands {
CommandGroup(replacing: .textFormatting) {
Button(action: {
// ⚠️ The currently focused TextView is retrieved and its AttributedString updated
guard let focusedTextView = model.focusedTextView else { return }
let newAttString = NSMutableAttributedString(string: "Value set through menu item")
newAttString.addAttribute(.backgroundColor, value: NSColor.yellow, range: NSRange(location: 0, length: 3))
focusedTextView.textStorage?.setAttributedString(newAttString)
focusedTextView.didChangeText()
}) {
Text("Insert image")
}.disabled(!model.menuItemEnabled)
}
}
}
}
