How do I work around a Mac Catalyst framework bug where no Core Animation output is shown in an export session?

This is verified to be a framework bug (occurs on Mac Catalyst but not iOS or iPadOS), and it seems the culprit is AVVideoCompositionCoreAnimationTool?

/// Exports a video with the target animating.
    func exportVideo() {
        let destinationURL = createExportFileURL(from: Date())
        guard let videoURL = Bundle.main.url(forResource: "black_video", withExtension: "mp4") else {
            delegate?.exporterDidFailExporting(exporter: self)
            print("Can't find video")
            return
        }

        // Initialize the video asset
        let asset = AVURLAsset(url: videoURL, options: [AVURLAssetPreferPreciseDurationAndTimingKey: true])
        guard let assetVideoTrack: AVAssetTrack = asset.tracks(withMediaType: AVMediaType.video).first,
              let assetAudioTrack: AVAssetTrack = asset.tracks(withMediaType: AVMediaType.audio).first else { return }
        let composition = AVMutableComposition()
        guard let videoCompTrack = composition.addMutableTrack(withMediaType: AVMediaType.video, preferredTrackID: Int32(kCMPersistentTrackID_Invalid)),
              let audioCompTrack = composition.addMutableTrack(withMediaType: AVMediaType.audio, preferredTrackID: Int32(kCMPersistentTrackID_Invalid)) else { return }
        videoCompTrack.preferredTransform = assetVideoTrack.preferredTransform

        // Get the duration
        let videoDuration = asset.duration.seconds

        // Get the video rect
        let videoSize = assetVideoTrack.naturalSize.applying(assetVideoTrack.preferredTransform)
        let videoRect = CGRect(origin: .zero, size: videoSize)

        // Initialize the target layers and animations
        animationLayers = TargetView.initTargetViewAndAnimations(atPoint: CGPoint(x: videoRect.midX, y: videoRect.midY), atSecondsIntoVideo: 2, videoRect: videoRect)

        // Set the playback speed
        let duration = CMTime(seconds: videoDuration,
                              preferredTimescale: CMTimeScale(600))
        let appliedRange = CMTimeRange(start: .zero, end: duration)
        videoCompTrack.scaleTimeRange(appliedRange, toDuration: duration)
        audioCompTrack.scaleTimeRange(appliedRange, toDuration: duration)

        // Create the video layer.
        let videolayer = CALayer()
        videolayer.frame = CGRect(origin: .zero, size: videoSize)

        // Create the parent layer.
        let parentlayer = CALayer()
        parentlayer.frame = CGRect(origin: .zero, size: videoSize)
        parentlayer.addSublayer(videolayer)

        let times = timesForEvent(startTime: 0.1, endTime: duration.seconds - 0.01)
        let timeRangeForCurrentSlice = times.timeRange
        // Insert the relevant video track segment
        do {
            try videoCompTrack.insertTimeRange(timeRangeForCurrentSlice, of: assetVideoTrack, at: .zero)
            try audioCompTrack.insertTimeRange(timeRangeForCurrentSlice, of: assetAudioTrack, at: .zero)
        }
        catch let compError {
            print("TrimVideo: error during composition: \(compError)")
            delegate?.exporterDidFailExporting(exporter: self)
            return
        }

        // Add all the non-nil animation layers to be exported.
        for layer in animationLayers.compactMap({ $0 }) {
            parentlayer.addSublayer(layer)
        }

        // Configure the layer composition.
        let layerComposition = AVMutableVideoComposition()
        layerComposition.frameDuration = CMTimeMake(value: 1, timescale: 30)
        layerComposition.renderSize = videoSize
        layerComposition.animationTool = AVVideoCompositionCoreAnimationTool(
            postProcessingAsVideoLayer: videolayer,
            in: parentlayer)
        let instructions = initVideoCompositionInstructions(
            videoCompositionTrack: videoCompTrack, assetVideoTrack: assetVideoTrack)
        layerComposition.instructions = instructions

        // Creates the export session and exports the video asynchronously.
        guard let exportSession = initExportSession(
                composition: composition,
                destinationURL: destinationURL,
                layerComposition: layerComposition) else {
            delegate?.exporterDidFailExporting(exporter: self)
            return
        }
        // Execute the exporting
        exportSession.exportAsynchronously(completionHandler: {
            if let error = exportSession.error {
                print("Export error: \(error), \(error.localizedDescription)")
            }
            self.delegate?.exporterDidFinishExporting(exporter: self, with: destinationURL)
        })
    }

Not sure how to implement a custom compositor that performs the same animations as this reproducible case:

class AnimationCreator: NSObject {

    // MARK: - Target Animations

    /// Creates the target animations.
    static func addAnimationsToTargetView(_ targetView: TargetView, startTime: Double) {
        // Add the appearance animation
        AnimationCreator.addAppearanceAnimation(on: targetView, defaultBeginTime: AVCoreAnimationBeginTimeAtZero, startTime: startTime)
        // Add the pulse animation.
        AnimationCreator.addTargetPulseAnimation(on: targetView, defaultBeginTime: AVCoreAnimationBeginTimeAtZero, startTime: startTime)
    }

    /// Adds the appearance animation to the target
    private static func addAppearanceAnimation(on targetView: TargetView, defaultBeginTime: Double = 0, startTime: Double = 0) {
        // Starts the target transparent and then turns it opaque at the specified time
        targetView.targetImageView.layer.opacity = 0
        let appear = CABasicAnimation(keyPath: "opacity")
        appear.duration = .greatestFiniteMagnitude // stay on screen forever
        appear.fromValue = 1.0 // Opaque
        appear.toValue = 1.0 // Opaque
        appear.beginTime = defaultBeginTime + startTime
        targetView.targetImageView.layer.add(appear, forKey: "appear")
    }

    /// Adds a pulsing animation to the target.
    private static func addTargetPulseAnimation(on targetView: TargetView, defaultBeginTime: Double = 0, startTime: Double = 0) {
        let targetPulse = CABasicAnimation(keyPath: "transform.scale")
        targetPulse.fromValue = 1 // Regular size
        targetPulse.toValue = 1.1 // Slightly larger size
        targetPulse.duration = 0.4
        targetPulse.beginTime = defaultBeginTime + startTime
        targetPulse.autoreverses = true
        targetPulse.repeatCount = .greatestFiniteMagnitude
        targetView.targetImageView.layer.add(targetPulse, forKey: "pulse_animation")
    }
}

For Apple engineers, this was filed as FB12878481.

How do I work around a Mac Catalyst framework bug where no Core Animation output is shown in an export session?
 
 
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