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Does the canvas view on top of the PDFView not re-render?
I added a canvas view using PDFPageOverlayViewProvider. When I zoom the PDFView, the drawing is scaled, but its quality becomes blurry. How can I fix this? import SwiftUI import PDFKit import PencilKit import CoreGraphics struct ContentView: View { var body: some View { if let url = Bundle.main.url(forResource: "sample", withExtension: "pdf"), let data = try? Data(contentsOf: url), let document = PDFDocument(data: data) { PDFRepresentableView(document: document) } else { Text("fail") } } } #Preview { ContentView() } struct PDFRepresentableView: UIViewRepresentable { let document: PDFDocument let pdfView = PDFView() func makeUIView(context: Context) -> PDFView { pdfView.displayMode = .singlePageContinuous pdfView.usePageViewController(false) pdfView.displayDirection = .vertical pdfView.pageOverlayViewProvider = context.coordinator pdfView.document = document pdfView.autoScales = false pdfView.minScaleFactor = 0.7 pdfView.maxScaleFactor = 4 return pdfView } func updateUIView(_ uiView: PDFView, context: Context) { // Optional: update logic if needed } func makeCoordinator() -> CustomCoordinator { return CustomCoordinator(parent: self) } } class CustomCoordinator: NSObject, PDFPageOverlayViewProvider, PKCanvasViewDelegate { let parent: PDFRepresentableView init(parent: PDFRepresentableView) { self.parent = parent } func pdfView(_ view: PDFView, overlayViewFor page: PDFPage) -> UIView? { let result = UIView() let canvasView = PKCanvasView() canvasView.drawingPolicy = .anyInput canvasView.tool = PKInkingTool(.pen, color: .blue, width: 20) canvasView.translatesAutoresizingMaskIntoConstraints = false result.addSubview(canvasView) NSLayoutConstraint.activate([ canvasView.leadingAnchor.constraint(equalTo: result.leadingAnchor), canvasView.trailingAnchor.constraint(equalTo: result.trailingAnchor), canvasView.topAnchor.constraint(equalTo: result.topAnchor), canvasView.bottomAnchor.constraint(equalTo: result.bottomAnchor) ]) for subView in view.documentView?.subviews ?? [] { subView.isUserInteractionEnabled = true } result.layoutIfNeeded() return result } }
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157
Jul ’25
CanvasView overlay on PDFKit loses quality when zoomed – how to preserve drawing resolution?
Hi all, I’m currently building a SwiftUI app that overlays a PKCanvasView onto each page of a PDFView using PDFPageOverlayViewProvider. It works well at the initial scale, but once I zoom into the PDF, the drawings on the PKCanvasView appear blurry or pixelated, even though the PDF itself remains crisp. I’m trying to adjust canvasView.contentScaleFactor relative to pdfView.scaleFactor to preserve the drawing quality. Here’s a simplified version of the relevant code: import SwiftUI import PDFKit import PencilKit struct ContentView: View { var body: some View { if let url = Bundle.main.url(forResource: "sample", withExtension: "pdf"), let data = try? Data(contentsOf: url), let document = PDFDocument(data: data) { PDFRepresentableView(document: document) } else { Text("") } } } #Preview { ContentView() } struct PDFRepresentableView: UIViewRepresentable { let document: PDFDocument let pdfView = PDFView() func makeUIView(context: Context) -> PDFView { pdfView.displayMode = .singlePageContinuous pdfView.usePageViewController(false) pdfView.displayDirection = .vertical pdfView.pageOverlayViewProvider = context.coordinator pdfView.document = document pdfView.autoScales = false pdfView.minScaleFactor = 0.7 pdfView.maxScaleFactor = 4 NotificationCenter.default.addObserver( context.coordinator, selector: #selector(context.coordinator.onPageZoomAndPan), name: .PDFViewScaleChanged, object: pdfView ) return pdfView } func updateUIView(_ uiView: PDFView, context: Context) { // Optional: update logic if needed } func makeCoordinator() -> CustomCoordinator { return CustomCoordinator(parent: self) } } class CustomCoordinator: NSObject, PDFPageOverlayViewProvider, PKCanvasViewDelegate { let parent: PDFRepresentableView init(parent: PDFRepresentableView) { self.parent = parent } func pdfView(_ view: PDFView, overlayViewFor page: PDFPage) -> UIView? { let canvasView = PKCanvasView() let rect = page.bounds(for: .mediaBox) canvasView.drawingPolicy = .anyInput canvasView.tool = PKInkingTool(.pen, color: .black, width: 10) canvasView.translatesAutoresizingMaskIntoConstraints = true canvasView.backgroundColor = .red.withAlphaComponent(0.1) canvasView.frame = rect canvasView.isScrollEnabled = false for subView in view.documentView?.subviews ?? [] { subView.isUserInteractionEnabled = true } return canvasView } @objc func onPageZoomAndPan() { parent.pdfView.documentView?.subviews.forEach { subview in if subview.theClassName == "PDFPageView", let pageViewPrivate = subview.value(forKey: "_private") as? NSObject, let page = pageViewPrivate.value(forKey: "page") as? PDFPage { subview.subviews.forEach { subview in if let canvasView = subview as? PKCanvasView { let zoomScale = parent.pdfView.scaleFactor canvasView.contentScaleFactor = UIScreen.main.scale * zoomScale canvasView.drawing = canvasView.drawing canvasView.setNeedsDisplay() canvasView.layoutIfNeeded() } } } } print("Zoom changed. Current scale: \(parent.pdfView.scaleFactor)") } } extension NSObject { var theClassName: String { return NSStringFromClass(type(of: self)) } } But this doesn’t seem to improve the rendered quality. The lines still appear blurry when zoomed in. What I’ve tried: • Adjusting contentScaleFactor and forcing redraw • Reassigning canvasView.drawing • Calling setNeedsDisplay() and layoutIfNeeded() None of these approaches seem to re-render the canvas at a higher resolution or match the zoomed scale of the PDF. My questions: 1. Is there a correct way to scale PKCanvasView content to match PDF zoom levels? 2. Should I recreate the canvas or drawing when zoom changes? 3. Is PKCanvasView just not intended to handle high zoom fidelity? If anyone has successfully overlaid high-resolution canvas drawing on a zoomable PDFView, I’d love to hear how you managed it. Thanks in advance!
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78
Jul ’25
Does LazyVStack and LazyVGrid release views from memory inside a ScrollView?
I am using LazyVStack inside a ScrollView. I understand that lazy views are rendered only when they come into view. However, I haven’t heard much about memory deallocation. I observed that in iOS 18 and later, when scrolling up, the bottom-most views are deallocated from memory, whereas in iOS 17, they are not (Example 1). Additionally, I noticed a similar behavior when switching views using a switch. When switching views by pressing a button, the view was intermittently deinitialized. (Example 2). Example 1) struct ContentView: View { var body: some View { ScrollView { LazyVStack { ForEach(0..<40) { index in CellView(index: index) } } } .padding() } } struct CellView: View { let index: Int @StateObject var viewModel = CellViewModel() var body: some View { Rectangle() .fill(Color.accentColor) .frame(width: 300, height: 300) .overlay { Text("\(index)") } .onAppear { viewModel.index = index } } } class CellViewModel: ObservableObject { @Published var index = 0 init() { print("init") } deinit { print("\(index) deinit") } } #Preview { ContentView() } Example 2 struct ContentView: View { @State var index = 0 var body: some View { LazyVStack { Button(action: { if index > 5 { index = 0 } else { index += 1 } }) { Text("plus index") } MidCellView(index: index) } .padding() } } struct MidCellView: View { let index: Int var body: some View { switch index { case 1: CellView(index: 1) case 2: CellView(index: 2) case 3: CellView(index: 3) case 4: CellView(index: 4) default: CellView(index: 0) } } } struct CellView: View { let index: Int @StateObject var viewModel = CellViewModel() var body: some View { Rectangle() .fill(Color.accentColor) .frame(width: 300, height: 300) .overlay { Text("\(index)") } .onAppear { viewModel.index = index } } } class CellViewModel: ObservableObject { @Published var index = 0 init() { print("init") } deinit { print("\(index) deinit") } } -------------------- init init init init init 2 deinit 3 deinit 4 deinit init
Topic: UI Frameworks SubTopic: SwiftUI
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300
Feb ’25
not work paragraphStyle in AttributedString
I tried to create a Text View using attributedString. I want to set the line height using paragraphStyle and return the Text, but paragraphStyle is not being applied. Why is that? extension Text { init?(_ content: String, font: StyleType, color: Color = .ppBlack) { var attributedString = AttributedString(content) attributedString.font = Font.custom(font.fontWeight, fixedSize: font.fontSize) attributedString.foregroundColor = color let paragraphStyle = NSMutableParagraphStyle() paragraphStyle.minimumLineHeight = 16 paragraphStyle.maximumLineHeight = 16 paragraphStyle.lineSpacing = 0 attributedString.mergeAttributes(.init([.paragraphStyle: paragraphStyle])) self = Text(attributedString) } }
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305
Feb ’25
how to change overlay View in PDFPageOverlayViewProvider
I’m using PDFPageOverlayViewProvider with pdfview. I want to control the visibility of the overlay view using a button. However, the view updates only when it disappears and reappears. I would like the changes to be reflected immediately. How can I achieve this? struct PDFKitView: View { let bookId: UUID let bookTitle: String @State private var currentPage = "1" @State private var isSideTab = false @State private var selectedNote: [SelectedNote] = [] var body: some View { let pdfDocument = openPDF(at: bookId.uuidString) ZStack(alignment: .trailing) { HStack(spacing: 0) { PDFKitRepresentableView( bookId: bookId, selectedNote: $selectedNote, currentPage: $currentPage, pdfDocument: pdfDocument ) if isSideTab { SideView() .transition(.move(edge: .trailing)) .zIndex(1) .frame(maxWidth: 260) } } .padding(.top, 73) } .onAppear { getAllNote(bookId: bookId) } .customNavigationBar(back: true) { Text("\(currentPage)/\(pdfDocument.pageCount)") .pretendard(.CaptionRegular) .foregroundStyle(Color.Text.primary) } TrailingView: { Button(action: { withAnimation { isSideTab.toggle() } }) { Image(systemName: SFSymbol.squareStack3dDownForwardFill.icon) .sfPro(.IconMedium) .foregroundStyle(Color.Text.primary) } } } @ViewBuilder func SideView() -> some View { VStack(spacing: 16) { HStack(spacing: 4) { Image(systemName: SFSymbol.squareStack3dDownForwardFill.icon) .sfPro(.IconSmall) .foregroundStyle(Color.Text.primary) Text(Literals.sideTabTitle) .pretendard(.P2Bold) .foregroundStyle(Color.Text.primary) Spacer() } .padding(16) .background { Color.Background.white } ScrollView { ForEach($selectedNote, id: \.noteId) { note in NoteCellView(note: note) } } .background { Color.Fill.white } } .background { Color.Background.blueGray } } @ViewBuilder func NoteCellView(note: Binding<SelectedNote>) -> some View { HStack(alignment: .top, spacing: 16) { Image(.writingNote) .resizable() .scaledToFit() .frame(width: 42, height: 60) VStack(alignment: .leading, spacing: 8) { Text(note.wrappedValue.noteId == bookId.uuidString ? "345" : "123") .foregroundStyle(Color.Text.secondary) .padding(.horizontal, 8) .background { Rectangle() .strokeBorder(Color.Layout.secondary) } Text(bookTitle) .lineLimit(2) Toggle("", isOn: note.selected) .labelsHidden() .tint(Color.Fill.activePrimary) } } .padding(EdgeInsets(top: 20, leading: 16, bottom: 16, trailing: 16)) } } struct PDFKitRepresentableView: UIViewRepresentable { let bookId: UUID @Binding var selectedNote: [SelectedNote] @Binding var currentPage: String let pdfDocument: PDFDocument let pdfView = PDFView() let toolPicker = PKToolPicker() func makeUIView(context: Context) -> PDFView { pdfView.displayMode = .singlePageContinuous pdfView.usePageViewController(false) pdfView.displayDirection = .vertical pdfView.pageOverlayViewProvider = context.coordinator pdfView.autoScales = true pdfDocument.delegate = context.coordinator pdfView.document = pdfDocument return pdfView } func updateUIView(_ uiView: PDFView, context: Context) { if let localNote = selectedNote.first(where: {$0.noteId == bookId.uuidString}), !localNote.selected { toolPicker.setVisible(false, forFirstResponder: uiView) } else { toolPicker.setVisible(true, forFirstResponder: uiView) } uiView.becomeFirstResponder() } func makeCoordinator() -> CanvasProvider { return CanvasProvider(parent: self) } } final class CanvasProvider: NSObject, PDFPageOverlayViewProvider, PDFDocumentDelegate { var localNotes = [PDFPage: PKCanvasView]() var passNotes = [PDFPage: Image]() let parent: PDFKitRepresentableView init(parent: PDFKitRepresentableView) { self.parent = parent super.init() getDrawingDatas( bookId: parent.bookId.uuidString, selectedNote: parent.selectedNote, document: parent.pdfDocument ) } func pdfView(_ view: PDFView, overlayViewFor page: PDFPage) -> UIView? { var coverView: PKCanvasView? = PKCanvasView() if let view = localNotes[page], parent.selectedNote.first(where: { $0.noteId == parent.bookId.uuidString })?.selected ?? false { view.backgroundColor = .clear view.isOpaque = true view.drawingPolicy = .anyInput view.delegate = self parent.toolPicker.addObserver(view) coverView = view (page as? CanvasPDFPage)?.canvasView = view } else { coverView = nil } for subView in view.documentView?.subviews ?? [] { if subView.theClassName == "PDFPageView" { subView.isUserInteractionEnabled = true } } return coverView } func pdfView(_ pdfView: PDFView, willDisplayOverlayView overlayView: UIView, for page: PDFPage) { } func pdfView(_ pdfView: PDFView, willEndDisplayingOverlayView overlayView: UIView, for page: PDFPage) { } }
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639
Aug ’24
When using index in a ForEach loop in SwiftUI, you might encounter an "index out of range" error.
I encountered a problem while using ScrollView in SwiftUI. When I perform a refresh, the app crashes. I access the array using an index in a ForEach loop. This is done to create new data from the array in a commonly used view. The function to create data is adopted from a protocol in the view model. I access it by index because the type of the array is not specified; each view using it may have a different data type. Below is an example code. Is it possible to access data from the array using an index? Every time I refresh, I get an "index out of range" error. import SwiftUI struct ContentView: View { @StateObject var viewModel = ViewModel() var body: some View { ScrollView { if !viewModel.testValues.isEmpty { LazyVStack(spacing: 20) { ForEach(Array(zip(viewModel.testValues.indices, viewModel.testValues)), id:\.1) { index, data in test(index: index, data: data, viewModel: viewModel) .onAppear { if !viewModel.isLoading, viewModel.testValues.count - 2 == index { viewModel.fetch() } } } } } else { Text("tesetsetsetsettse") } } .onAppear { viewModel.fetch() } .refreshable { viewModel.refresh() } } } struct test: View { let index: Int let data: String @ObservedObject var viewModel: ViewModel var body: some View { VStack(spacing: 8) { test1(index: index, data: data, viewModel: viewModel) Text("------------------------") } } } struct test1: View { let index: Int let data: String @ObservedObject var viewModel: ViewModel var body: some View { VStack { Text(viewModel.testValues[index]) .font(.system(size: 12)) .foregroundStyle(Color.red) .padding(.horizontal, 40) .padding(.vertical, 50) .background { RoundedRectangle(cornerRadius: 20) .fill(Color.blue) } } } } class ViewModel: ObservableObject { @Published var isLoading = false @Published var testValues: [String] = [] func fetch() { DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { self.testValues += [ UUID().uuidString, UUID().uuidString, UUID().uuidString, UUID().uuidString, UUID().uuidString, UUID().uuidString, UUID().uuidString, UUID().uuidString, UUID().uuidString, UUID().uuidString, ] } } func refresh() { testValues = [] fetch() } }
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1.4k
Apr ’24