最常见的是这个： Thread 1 Queue : com.apple.main-thread (serial) #0 0x0000000190bcb3c4 in CFRelease.cold.2 () #1 0x0000000190a2c50c in CFRelease () #2 0x00000001d194ad38 in -[PDFTileSurface releaseSurface] () #3 0x00000001d194c230 in -[PDFTilePool releasePDFTileSurface:] () #4 0x00000001d194f618 in -[PDFPageLayerTile dealloc] () #5 0x0000000190a4778c in -[__NSArrayI_Transfer dealloc] () #6 0x000000018d5d57f8 in AutoreleasePoolPage::releaseUntil () #7 0x000000018d5d5684 in objc_autoreleasePoolPop () #8 0x000000019668d43c in -[UIScrollView setContentOffset:] () #9 0x000000018dd70918 in -[NSObject(NSKeyValueObservingPrivate) _changeValueForKeys:count:maybeOldValuesDict:maybeNewValuesDict:usingBlock:] () #10 0x000000018ddd1298 in -[NSObject(NSKeyValueObservingPrivate) _changeValueForKey🔑 key:usingBlock:] () #11 0x000000018ded5b28 in _NSSetPointValueAndNotify () #12 0x0000000196c49af0 in -[UIScrollView _smoothScrollSyncWithUpdateTime:] () #13 0x0000000196c491a0 in -[UIScrollView _smoothScrollWithUpdateTime:] () #14 0x0000000196c490b0 in -[UIScrollView smoothScrollDisplayLink:] () #15 0x000000026186a66c in -[DYDisplayLinkInterposer forwardDisplayLinkCallback:] () #16 0x00000001914cc77c in CA::Display::DisplayLinkItem::dispatch () #17 0x00000001914a4388 in CA::Display::DisplayLink::dispatch_items () #18 0x00000001914bb2b8 in CA::Display::DisplayLink::dispatch_deferred_display_links () #19 0x000000019671e2a8 in _UIUpdateSequenceRunNext () #20 0x000000019671b834 in schedulerStepScheduledMainSectionContinue () #21 0x00000002a437256c in UC::DriverCore::continueProcessing () #22 0x0000000190a3f1d8 in __CFMachPortPerform () #23 0x0000000190a81824 in CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION () #24 0x0000000190a8174c in __CFRunLoopDoSource1 () #25 0x0000000190a4c6e4 in __CFRunLoopRun () #26 0x0000000190a4b54c in _CFRunLoopRunSpecificWithOptions () #27 0x0000000235da7498 in GSEventRunModal () #28 0x0000000196744244 in -[UIApplication _run] () #29 0x00000001966af158 in UIApplicationMain () #30 0x00000001968bb618 in ___lldb_unnamed_symbol_1893835b0 () #31 0x0000000105a7a308 in static UIApplicationDelegate.main() () #32 0x0000000105a7a278 in static AppDelegate.$main() () #33 0x0000000105a7a3cc in main () #34 0x000000018d659c1c in start ()
Thanks for the report, and for including the crash log.
I built a test on iOS 26 with the same combination: a PDFView with an overlaid PKCanvasView. I then stress-tested it on an iPad. It zoomed repeatedly to about 9x and back while running animated smooth scrolls. I also pinch-zoomed deep into a page and flick-scrolled quickly. I could not reproduce the crash using Apple frameworks alone.
Here is how I read your stack. The crash is an over-release. During a display-link-driven smooth scroll, setting the content offset drains an autorelease pool. That deallocates PDFKit tiles, and CFRelease then hits its error path (CFRelease.cold.2) while releasing a tile surface. That signature means an object is released one time too many.
One frame in the stack is not part of PDFKit, UIKit, or CoreAnimation: -[DYDisplayLinkInterposer forwardDisplayLinkCallback:]. This is code in your app, so you will know what it is. It intercepts and forwards the CADisplayLink callback that drives the smooth scroll where the crash occurs. It sits directly in the failing path and affects scroll timing. So a useful next step is to find out whether the crash still occurs without it.
Here is a way to isolate it:
- Reproduce with
DYDisplayLinkInterposerdisabled or removed, so the display-link callback runs without it. If the crash stops, that isolates it toDYDisplayLinkInterposer. If it still crashes without it, that points at PDFKit. - If it still reproduces with only Apple frameworks, please file a report with Feedback Assistant. A small sample project that crashes with just PDFKit and PencilKit is the key piece. Include a sysdiagnose captured right after the crash and the symbolicated crash report, so the team can investigate directly.
- It would also help to know how your PDFView and PKCanvasView are composited, in particular whether the canvas tracks the PDF's zoom and scroll. That matters in case the integration is involved.
Since heavy zoom and scrolling did not reproduce it here with PDFKit and PencilKit by themselves, isolating DYDisplayLinkInterposer is where I would start.
Please let me know what you find.