fix(ios): guard unsupportedCaptureOutputClasses against SimCam crash on simulator#3826
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therealpurplemana wants to merge 1 commit intomrousavy:mainfrom
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fix(ios): guard unsupportedCaptureOutputClasses against SimCam crash on simulator#3826therealpurplemana wants to merge 1 commit intomrousavy:mainfrom
therealpurplemana wants to merge 1 commit intomrousavy:mainfrom
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…ent(simulator) SimCam injects a DummyCaptureDeviceFormat into the iOS Simulator to fake camera input. When VisionCamera's ConstraintResolver calls supportsOutput() on startup, it reads unsupportedCaptureOutputClasses, which internally calls isStreamingDisparitySupported. That method crashes with SIGSEGV (null pointer dereference at offset 0x59) because SimCam's dummy format doesn't implement it. On simulator, skip the output class check entirely — the camera is fake anyway and all outputs can be assumed supported. Crash stack: AVCaptureDeviceFormat.isStreamingDisparitySupported <-- SIGSEGV AVCaptureDeviceFormat.unsupportedCaptureOutputClasses AVCaptureDeviceFormat.supportsOutput (this file) ConstraintResolver.filterFormats HybridCameraSession.configureConnection
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Owner
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It sounds like that might be a bug in SimCam though, if it crashes there? |
Author
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It’s hard to say. It might be. But removing the check in a simulator
environment should be low enough risk to let us further expose that or
encourage them to fix upstream. It seems to occur because the SimCam
doesn’t expose the camera information in time for RNVC.
…On Wed, Apr 29, 2026 at 11:51 PM Marc Rousavy ***@***.***> wrote:
*mrousavy* left a comment (mrousavy/react-native-vision-camera#3826)
<#3826 (comment)>
It sounds like that might be a bug in SimCam though, if it crashes there?
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Owner
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Apparently this has been fixed upstream in StreamCam today, so we shouldn't need this workaround anymore :) Thanks anyways! |
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Problem
When using SimCam (Software Mansion's simulator camera injection tool) with VisionCamera on the iOS Simulator, the app crashes immediately on launch with
EXC_BAD_ACCESS (SIGSEGV)on thecom.margelo.camera.sessionqueue.Crash stack:
Root cause: SimCam injects a
DummyCaptureDeviceFormatinto the simulator. WhenConstraintResolver.filterFormatscallsformat.supportsOutput()for each camera format at session startup, it readsunsupportedCaptureOutputClasses, which internally callsisStreamingDisparitySupported. SimCam's dummy format has a null ivar at offset0x59for this property, causing the crash.Fix
Guard
unsupportedCaptureOutputClassesbehind#if targetEnvironment(simulator). On the simulator the camera is fake regardless, so assuming all outputs are supported is correct and safe.Testing
Tested on iOS Simulator (iOS 26.3) with SimCam running — app no longer crashes on launch and the simulated camera feed displays correctly. Tested iPhone Air device confirming camera working correctly. Tested on Android Pixel 8 confirming camera working correctly.