Issues with @preconcurrency and AVFoundation in Swift 6 on Xcode 16.1/iOS 18 (Worked fine in Swift 5)

Question:

I'm working on a project in Xcode 16.1, using Swift 6 with iOS 18. My code is working fine in Swift 5, but I'm running into concurrency issues when upgrading to Swift 6, particularly with the @preconcurrency attribute in AVFoundation.

Here is the relevant part of my code:

import SwiftUI
@preconcurrency import AVFoundation

struct OverlayButtonBar: View {

    ...
    let audioTracks = await loadTracks(asset: asset, mediaType: .audio)
    ...

    // Tracks are extracted before crossing concurrency boundaries
    private func loadTracks(asset: AVAsset, mediaType: AVMediaType) async -> [AVAssetTrack] {
        do {
            return try await asset.load(.tracks).filter { $0.mediaType == mediaType }
        } catch {
            print("Error loading tracks: \(error)")
            return []
        }
    }
}

Issues:

When using @preconcurrency, I get the warning:

@preconcurrency attribute on module AVFoundation has no effect. Suggested fix by Xcode is: Remove @preconcurrency.

But if I remove @preconcurrency, I get both a warning and an error:

• Warning: Add '@preconcurrency' to treat 'Sendable'-related errors from module 'AVFoundation' as warnings.
• Error: Non-sendable type [AVAssetTrack] returned by implicitly asynchronous call to nonisolated function cannot cross actor boundary. (Class AVAssetTrack does not conform to the Sendable protocol (AVFoundation.AVAssetTrack)). This error comes if I attempt to directly access non-Sendable AVAssetTrack in an async context :

let audioTracks = await loadTracks(asset: asset, mediaType: .audio)

How can I resolve this issue while staying compliant with Swift 6 concurrency rules? Is there a recommended approach to handling non-Sendable types like AVAssetTrack in concurrency contexts?

Appreciate any guidance on making this work in Swift 6, especially considering it worked fine in Swift 5.

Thanks in advance!