从不同的角色设置 UnsafeMutablePointer 指针对象

Question

UnsafeMutablePointer

不再是 Sendable，并且在 Xcode 16 Beta 中使用构建设置“严格并发检查”，从另一个 pointee

 设置 

pointer

 的 

actor

（正确吗？）会发出警告。 

设置：

问题：

下面的代码给出警告

Capture of 'shouldStopPointer' with non-sendable type 'UnsafeMutablePointer<ObjCBool>' in a @Sendable closure; this is an error in the Swift 6 language mode. Generic struct 'UnsafeMutablePointer' does not conform to the 'Sendable' protocol (Swift.UnsafeMutablePointer)

如何将指针设置在正确的演员中，或者以其他方式防止此警告？

截图：

代码：

import SwiftUI import Photos

actor DifferentActor {
    func requestMetaData(progressHandler: @escaping PHAssetImageProgressHandler) async -> CGImagePropertyOrientation {
        let options = PHImageRequestOptions()
        options.isNetworkAccessAllowed = true
        options.deliveryMode = .opportunistic
        options.progressHandler = progressHandler
        
        let someAsset = PHAsset()
        
        let orientation = await withCheckedContinuation { continuation in
            PHImageManager.default().requestImageDataAndOrientation(for: someAsset, options: options) { imageData, dataUTI, orientation, status in
                continuation.resume(returning: orientation)
            }
        }
        return orientation
    } }

@MainActor struct ContentView: View {
    let differentActor = DifferentActor()
    
    @State var photoMetadata: String?
    
    @State var progress: Double = 0.0
    
    @State var shouldStopGettingMetadata: Bool = false
    
    var body: some View {
        VStack(spacing: 20) {
            
            Button("Get metadata") {
                Task {
                    await downloadMetaData()
                }
            }
            
            HStack {
                Text("Progress: ")
                ProgressView(value: progress)
            }
            
            Button("Cancel get metadata") {
                shouldStopGettingMetadata = true
            }
            
            Text("Orientation: \(photoMetadata ?? "Not yet loaded")")
            
        }
    }
    
    private func downloadMetaData() async {
        let orientation = await differentActor.requestMetaData { @Sendable progress, error, shouldStopPointer, info in
            
            Task { @MainActor in
                self.progress = progress
                
                if self.shouldStopGettingMetadata {
                    shouldStopPointer.pointee = true
                }
            }
        }
        self.photoMetadata = "\(orientation)"
    }
     }

#Preview {
    ContentView() }

如果我将所有内容设为异步，则会收到不同的错误：

Cannot pass function of type '@Sendable (Double, (any Error)?, UnsafeMutablePointer<ObjCBool>, [AnyHashable : Any]?) async -> Void' to parameter expecting synchronous function type 截图：

代码：

private func downloadMetaData() async {
    let orientation = await differentActor.requestMetaData { @Sendable progress, error, shouldStopPointer, info in
        
        await self.progress = progress
        
        let shouldStop = self.shouldStopGettingMetadata
        
        if shouldStop {
            shouldStopPointer.pointee = true
        }
    }
    self.photoMetadata = "\(orientation)"
}

Answer 1

您需要使指针符合

@unchecked Sendable

extension UnsafeMutablePointer<ObjCBool>: @unchecked Sendable {} 或在 Xcode 16 中：

extension UnsafeMutablePointer<ObjCBool>: @unchecked @retroactive Sendable {} 请参阅

https://forums.swift.org/t/unsafepointer-sendable-should-be-revoked/51926 和 https://github.com/swiftlang/swift/pull/39218