Summary On iOS 18 and later, Chinese text rendering shows a noticeable performance regression related to the HVF (Hierarchical Variable Font) pipeline. Environment iOS Version: iOS 18+ Framework: libhvf.dylib (Hierarchical Variable Font) Affected Font: PingFangUI.ttc (private system font, automatically used for Chinese text) Related Frameworks: CoreText, CoreGraphics, FontParser Devices: All iOS devices (more noticeable on older hardware) Background iOS 18 Change: PingFang.ttc was removed from /System/Library/Fonts/ Private PingFangUI.ttc was added (inaccessible via normal font APIs) System automatically uses PingFangUI.ttc for all Chinese text rendering PingFangUI.ttc contains HVF tables → utilizes libhvf.dylib HVF Architecture: HVF (Hierarchical Variable Font) organizes glyphs as tree structures Each glyph = Composite → multiple Parts → nested hierarchy Rendering a single character requires traversing this tree Key Observation A single Chinese glyph typically triggers ~20 calls to HVF::LoaderHVGL::loadPartAtIndex. Cache invalidation is triggered via IncrementRenderCount after every 18 glyphs: __ZNK27THierVariationsDataForkFont20IncrementRenderCountEv: ldr w8, [x0, #0x12c] add w8, w8, #0x1 str w8, [x0, #0x12c] cmp w8, #0x12 b.lo return ldr x0, [x0, #0x120] bl HVF_clear_part_cache str wzr, [x19, #0x12c] return: ret This causes the cache to be cleared before a typical sentence finishes rendering. Complete Call Stack (Rendering Hot Path) #0-1 HVF::LoaderHVGL::loadPartAtIndex #2 HVF::FlatPartCache::partAtIndex #3 HVF::PartTransformRenderer::renderComposite #4 HVF::PartTransformRenderer::render #5 HVF::PartTransformRenderer::renderToContext #6 _HVF_render_current_part #7 THierVariationsFontHandler::GetOutlinePath #8 TFontHandler::CopyGlyphPath #9 THierVariationsFontHandler::CopyGlyphPath #10 TFPFont::CopyGlyphPath #11-12 TFPFont::CopyGlyphPath / _FPFontCopyGlyphPath #13 _CGFontCreateGlyphPath #14 _CGGlyphBuilderLockBitmaps #15 _render_glyphs #16 _draw_glyph_bitmaps #17 _ripc_DrawGlyphs #18 CG::DisplayList::executeEntries #19 _CGDisplayListDrawInContextDelegate #20 _CABackingStoreUpdate_ #21-22 CALayer display/layout #23-24 CA::Transaction::commit #25-30 UIApplicationMain / RunLoop HVF::LoaderHVGL::loadPartAtIndex is consistently observed as a hot function in Instruments and in production. Cache Clear Call Stack #0 HVF::FlatPartCache::clear #1 HVF_clear_part_cache #2 THierVariationsDataForkFont::IncrementRenderCount #3 THierVariationsFontHandler::GetOutlinePath #4 TFontHandler::CopyGlyphPath #5 FPFontCopyGlyphPath #6 CGFontCreateGlyphPath #7 _render_glyphs #8 _draw_glyph_bitmaps #9 _ripc_DrawGlyphs This shows that cache clearing occurs within the glyph rendering path. Impact For a typical Chinese sentence (~20 characters): Each glyph requires multiple part loads (~20 per glyph) Cache is cleared before rendering completes Previously loaded parts cannot be reused Observed effects: Increased loadPartAtIndex invocation count Low cache hit rate Increased CPU usage in glyph rendering Main-thread blocking during Core Animation commit Regression iOS 17 and earlier: Rendering is smooth under similar workloads. iOS 18+: Increased rendering cost and visible frame drops. The issue is more pronounced on older devices such as iPhone XS and iPhone 11. Reproduction Render a Chinese text string longer than 18 characters, for example: 刷新测试中文文本用于验证渲染性能问题需要超过十八个字 Observe: Repeated loadPartAtIndex calls Frequent cache clearing Request It would be helpful to review the cache eviction strategy for HVF, particularly for complex scripts such as Chinese. Potential considerations: Adjusting or scaling the cache threshold Avoiding full cache clears during continuous rendering Improving reuse of parts across glyphs within the same rendering batch

Hi, I'm using one ttf font that simulate a bitmap look in my app. However, macOS renders all font with anti-aliasing. On those kind of font, that introduce some artefacts. Is there a way to disable anti-aliasing or some tricks that would make like there were no anti-aliasing? Thanks.

Beginning with macOS Sonoma, Apple introduced a novel font format for rendering Chinese text. Apps that use third-party libraries for text rendering continued to function, primarily without disruption, owing to some workarounds provided by the operating system. FreeType, one of the most widely used cross-platform libraries for text rendering, now supports this new format. Apps that use this library, regardless of whether they encountered issues with Chinese text or not, should update to the latest FreeType source from their git repository (https://gitlab.freedesktop.org/freetype/freetype), as this support is not yet available in a tagged release. Updating ensures that apps operate optimally with Chinese text as well as any other language that uses this new format. Because this support calls into Apple APIs that Apple introduced in macOS 15.4, iOS 18.4, and aligned watchOS, tvOS, and visionOS releases, set the deployment target when building FreeType to match that of your own app. This ensures that the new API calls fail gracefully on older OS versions rather than causing your app to crash on systems where those APIs are not available.

My basic need is that I have unicode symbols which compose to a marked musical note. I'd like that note to be rotated upside down. Obviously, I could do this by sticking each into a View of some sort, and applying rotation effect. Indeed, I've done this for the part of my app where these notes are the labels of Buttons. However, the results of pressing the buttons need to be displayed, and on most of my app, this is a simple String. However, I can find no way to rotate individual glyphs of a String. And I'm not keen to write a compositor to layout View like glyphs in a String. Is there a way to make a font by finding individual glyphs, doing the transform, and packaging them into a new specialized font, without needed to use an external Font making application?

On macOS 26, how do you support the Preferred Text Size value as defined in the Accessibility Settings? Historically, "Dynamic Type" has not been available on macOS. However, the user has some control over text size through the Accessibility Settings. On macOS 26, a small subset of applications are honouring changes to that value include Finder, Mail, and sidebars in many applications. Dynamic sizing in table views has been available on macOS for awhile. But Mail.app, in particular, is also adjusting the font sizes used in the message's body pane while the Finder is adjusting font sizes used for Desktop icons. I can't find an NSNotification that is fired when the user adjusts the Accessibility Text Size slider, nor can I find an API to read the current value. NSFont.preferredFont(forTextStyle:options:) looks promising but the fonts returned do not appear to take the user's Accessibility setting into account. (Nor do they update dynamically.) SwiftUI's Text("Apple").font(.body) performs similarly to NSFont in that it does respect the style, but it does not honour dynamic sizing. NSFontDescriptor has a bunch of interesting methods, but none that seem to apply to Accessibility Text Size. Given an AppKit label: let label = NSTextField(labelWithString: "AppKit") label.font = NSFont.preferredFont(forTextStyle: .body) Or a SwiftUI label: Text("SwiftUI").font(.body) How do I make either of them responsive to the user's Text Size setting under Accessibility? Note this is on macOS 26 / Xcode 26. I realize there have been some previous forum posts related to this issue but hoping that things might have improved since then.

I'm a font developer. In the development process, I will revise a font and overwrite the OTF file that is currently enabled (registered) with macOS. If I then launch an app, it will immediately use the revised version of the font; while apps that are already loaded will continue to use the old version. This suggests that each app is loading new and separate font data, rather than getting it from some existing cache in memory. Yet macOS does have a "font cache" of some sort. Some apps, like TextEdit, seem to only load the fonts that they need to use. However, other apps, like Pages, load every enabled (registered) font on the OS!! (According to the Open Files list in Activity Monitor.) Given that /System/Library/Fonts/ is 625 Mb, and we can't disable any of it, isn't that a lot of data to be repeating? How many fonts is too many fonts? I can't find much documentation about the process.

Hi everyone, I’m trying to register fonts system-wide using CTFontManagerRegisterFontURLs with the .persistent scope. The fonts are delivered through Apple-Hosted Background Assets (since On-Demand Resources are deprecated). Process-level registration works perfectly, but persistent registration triggers a system “Install Fonts” prompt, and tapping Install causes the app to crash immediately. I’m wondering if anyone has successfully used Apple-Hosted Background Assets to provide persistent, system-wide installable fonts, or if this is a current OS limitation/bug. What I Expect Fonts delivered through Apple-Hosted Background Assets should be eligible for system-wide installation Tap “Install” should install fonts into Settings → Fonts just like app-bundled or ODR fonts App should not crash Why This Matters According to: WWDC 2019: Font Management and Text Scaling Developers can build font provider apps that install fonts system-wide, using bundled or On-Demand Resources. WWDC 2025: Discover Apple-Hosted Background Assets On-Demand Resources are deprecated, and AHBAs are the modern replacement. Therefore, persistent font installation via Apple-Hosted Background Assets appears to be the intended path moving forward. Question Is this a known limitation or bug in iOS? Should .persistent font installation work with Apple-Hosted Background Assets? Do we need additional entitlement, manifest configuration, or packaging rules? Any guidance or confirmation from Apple engineers would be greatly appreciated. Additional Info I submitted a Feedback including a minimal reproducible sample project: FB21109320

Hi! I am adding MacOS to a SwiftUI based multiplatform app in XCode, and have noticed an effect on the OTF font I am using. When started for a MacOSX target, the font looks a bit fuzzy, or too bold for the same display: Above is the display running in an iPhone 13 mini simulator, below the macOS version running for the "My Mac" target. The font is in both cases just fetched with static let tkDisplayFont = Font.custom("Segment7Standard", size: 38) Same applies in dark mode: This makes the numbers and especially the decimal point a bit harder to read. The same happens with the system font, but it is not such a problem there: I guess this is handled a bit differently between UIFont and NSFont underneath. Is there a way to tell the font to behave the same way as on iOS?

This code: import SwiftUI struct heightProblem: View { var body: some View { Text("\u{1D15E} \u{1D15F} \u{1D160} \u{1D161} \u{1D162} \u{1D163} \u{1D164}") .font(Font.largeTitle.bold()) .frame(height: 50.0) .border(.red) .padding() .border(.green) } } #Preview { heightProblem() } Produces this display: Note the clipping. Lowering the baseline by about 20 brings it into view, but this is a horrible fix for dynamic display (The font is Noto, which works just fine in Xcode, but not in Safari for some reason.)

Hello everyone, I am having an issue where the attributed text that I have in my UITextView is not scaling dynamically with phone text size, whenever I remove the attributed text logic, it scales fine, however, with it, it stays at a set font size. struct AutoDetectedClickableDataView: UIViewRepresentable { let text: String @Binding var height: CGFloat func makeUIView(context: Context) -> UITextView { let textView = UITextView() textView.dataDetectorTypes = [.phoneNumber, .address, .link] textView.isEditable = false textView.isScrollEnabled = false textView.backgroundColor = .clear textView.font = UIFont.preferredFont(forTextStyle: .body) /*UIFontMetrics(forTextStyle: .body).scaledFont(for: UIFont.systemFont(ofSize: 16.0)) */ textView.adjustsFontForContentSizeCategory = true textView.textContainer.lineBreakMode = .byWordWrapping textView.textContainerInset = .zero textView.textContainer.lineFragmentPadding = 0 textView.translatesAutoresizingMaskIntoConstraints = false textView.setContentCompressionResistancePriority(.defaultLow, for: .horizontal) textView.setContentHuggingPriority(.defaultHigh, for: .horizontal) return textView } func updateUIView(_ uiView: UITextView, context: Context) { let attributed = NSMutableAttributedString(string: text, attributes: [ .font: UIFont.preferredFont(forTextStyle: .body) ]) let detector = try? NSDataDetector(types: NSTextCheckingResult.CheckingType.address.rawValue | NSTextCheckingResult.CheckingType.link.rawValue | NSTextCheckingResult.CheckingType.phoneNumber.rawValue) detector?.enumerateMatches(in: text, options: [], range: NSRange(location: 0, length: text.utf16.count)) { match, _, _ in guard let match = match else { return } attributed.addAttributes([ .foregroundColor: UIColor.systemBlue, .underlineStyle: NSUnderlineStyle.single.rawValue, ], range: match.range) } uiView.attributedText = attributed // uiView.text = text DispatchQueue.main.async { uiView.layoutIfNeeded() let fittingSize = CGSize(width: uiView.bounds.width, height: .greatestFiniteMagnitude) let size = uiView.sizeThatFits(fittingSize) height = size.height } } }

Hi Support Team, I am new here. I am unable to add my fonts to the asset catalog there is no option to add new font set when I click the plus sign. When I drag my files in they show up as data. I have a Contents.json in the font folder called BeVietnamProFont.font. Is there something I am doing wrong? Thanks SO much! { "info": { "version": 1, "author": "xcode" }, "properties": {}, "fonts": [ { "filename": "BeVietnamPro-Black.ttf", "weight": "black", "style": "normal" }, { "filename": "BeVietnamPro-BlackItalic.ttf", "weight": "black", "style": "italic" }, { "filename": "BeVietnamPro-Bold.ttf", "weight": "bold", "style": "normal" }, { "filename": "BeVietnamPro-BoldItalic.ttf", "weight": "bold", "style": "italic" }, { "filename": "BeVietnamPro-ExtraBold.ttf", "weight": "heavy", "style": "normal" }, { "filename": "BeVietnamPro-ExtraBoldItalic.ttf", "weight": "heavy", "style": "italic" }, { "filename": "BeVietnamPro-ExtraLight.ttf", "weight": "ultralight", "style": "normal" }, { "filename": "BeVietnamPro-ExtraLightItalic.ttf", "weight": "ultralight", "style": "italic" }, { "filename": "BeVietnamPro-Light.ttf", "weight": "light", "style": "normal" }, { "filename": "BeVietnamPro-LightItalic.ttf", "weight": "light", "style": "italic" }, { "filename": "BeVietnamPro-Regular.ttf", "weight": "regular", "style": "normal" }, { "filename": "BeVietnamPro-Italic.ttf", "weight": "regular", "style": "italic" }, { "filename": "BeVietnamPro-Medium.ttf", "weight": "medium", "style": "normal" }, { "filename": "BeVietnamPro-MediumItalic.ttf", "weight": "medium", "style": "italic" }, { "filename": "BeVietnamPro-SemiBold.ttf", "weight": "semibold", "style": "normal" }, { "filename": "BeVietnamPro-SemiBoldItalic.ttf", "weight": "semibold", "style": "italic" }, { "filename": "BeVietnamPro-Thin.ttf", "weight": "thin", "style": "normal" }, { "filename": "BeVietnamPro-ThinItalic.ttf", "weight": "thin", "style": "italic" } ] } ![]("https://developer.apple.com/forums/content/attachment/56835f04-d1c1-468f-808b-9a786562d367" "title=Screenshot 2025-07-13 at 1.05.05 PM.png ;width=539;height=630")