使用Xcode Preview时Framework中CoreData崩溃问题求助

项目包含3个Target：

• 主应用
• 扩展程序
• 共享Framework（内置CoreData管理，已配置App Groups实现主应用和扩展数据共享）

使用Xcode Preview时出现崩溃，推测是沙箱限制访问/dev/null导致。

Persistence.swift（崩溃相关行标注） #

public struct PersistenceController {
    public static let shared = PersistenceController()

    public static var preview: PersistenceController = { // <---- 第14行
        let result = PersistenceController(inMemory: true)
        let viewContext = result.container.viewContext
        for _ in 0..<10 {
            let newItem = Item(context: viewContext)
            newItem.timestamp = Date()
        }
        do {
           try viewContext.save()
        } catch {
            let nsError = error as NSError
            fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
        }
        return result
    }()

    public let container: NSPersistentContainer

    public init(inMemory: Bool = false) {
        let groupName = "group.com.xxx"
        let fileName = "database.sqlite"

        container = NSPersistentContainer(name: "xxxxxx")
        if inMemory {
            container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null") // <--- 第68行
        }
        else {
            let containerURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: groupName)!
            let storeURL = containerURL.appendingPathComponent(fileName)
            let description = NSPersistentStoreDescription(url: storeURL)
            container.persistentStoreDescriptions = [description]
        }
        
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        container.viewContext.automaticallyMergesChangesFromParent = true
     }
}

ContentView.swift #

struct ContentView: View {
    var body: some View {
        VStack {
            Image(systemName: "globe")
                .imageScale(.large)
                .foregroundStyle(.tint)
            Text("Hello, world!")
        }
        .padding()
    }
}

#Preview {
    ContentView().environment(\.managedObjectContext, PersistenceController.preview.container.viewContext)
}

崩溃报告 #

Thread 0 Crashed::  Dispatch queue: com.apple.main-thread
0   libswiftCore.dylib                     0x102e0bf9e closure #1 in closure #1 in closure #1 in _assertionFailure(_:_:file:line:flags:) + 318
1   libswiftCore.dylib                     0x102e0be1e closure #1 in closure #1 in _assertionFailure(_:_:file:line:flags:) + 366
2   libswiftCore.dylib                     0x102e0bb5b closure #1 in _assertionFailure(_:_:file:line:flags:) + 123
3   libswiftCore.dylib                     0x102e0b816 _assertionFailure(_:_:file:line:flags:) + 230
4   CallerData                             0x101a46d36 PersistenceController.init(inMemory:) + 982 (Persistence.swift:68)
5   CallerData                             0x101a47423 closure #1 in variable initialization expression of static PersistenceController.preview + 51 (Persistence.swift:15)
6   CallerData                             0x101a473d9 one-time initialization function for preview + 9 (Persistence.swift:14)
7   libdispatch.dylib                      0x1040c6d3a _dispatch_client_callout + 8
8   libdispatch.dylib                      0x1040c80f3 _dispatch_once_callout + 20
9   CallerData                             0x101a474d1 PersistenceController.preview.unsafeMutableAddressor + 49 (Persistence.swift:14)
10  ContentView.1.preview-thunk.dylib          0x1019d0f48 closure #1 in static $s41ShieldUp_PreviewReplacement_ContentView_133_BD1FE069A66FD2100B578D7DDB7CD228Ll0C0fMf_15PreviewRegistryfMu_.makePreview() + 40 (@__swiftmacro_41ShieldUp_PreviewReplacement_ContentView_133_BD1FE069A66FD2100B578D7DDB7CD228Ll0C0fMf_.swift:9)
11  PreviewsInjection                      0x101d74386 0x101d36000 + 254854
12  PreviewsInjection                      0x101d7525d 0x101d36000 + 258653
13  libswift_Concurrency.dylib             0x103e026dc static MainActor.assumeIsolated<A>(_:file:line:) + 140
14  PreviewsInjection                      0x101d740e5 0x101d36000 + 254181
15  PreviewsInjection                      0x101d78108 0x101d36000 + 270600
16  PreviewsInjection                      0x101d78c1c 0x101d36000 + 273436
17  PreviewsInjection                      0x101d659fd 0x101d36000 + 195069
18  PreviewsInjection                      0x101d6886a 0x101d36000 + 206954
19  PreviewsInjection                      0x101d4f620 0x101d36000 + 103968
20  PreviewsInjection                      0x101d4fae4 0x101d36000 + 105188
21  PreviewsInjection                      0x101d6a3e0 0x101d36000 + 213984
22  PreviewsInjection                      0x101d3e3e3 0x101d36000 + 33763
23  PreviewsInjection                      0x101d3da75 0x101d36000 + 31349
24  PreviewsFoundation                     0x131969ed9 0x1318c9000 + 659161
25  libdispatch.dylib                      0x1040c5a90 _dispatch_call_block_and_release + 12
26  libdispatch.dylib                      0x1040c6d3a _dispatch_client_callout + 8
27  libdispatch.dylib                      0x1040d5ac0 _dispatch_main_queue_drain + 1420
28  libdispatch.dylib                      0x1040d5526 _dispatch_main_queue_callback_4CF + 31
29  CoreFoundation                         0x102344dc4 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
30  CoreFoundation                         0x10233f6ff __CFRunLoopRun + 2463
31  CoreFoundation                         0x10233e97d CFRunLoopRunSpecific + 557
32  GraphicsServices                       0x104ec108f GSEventRunModal + 137
33  UIKitCore                              0x116efc53d -[UIApplication _run] + 972
34  UIKitCore                              0x116f00fab UIApplicationMain + 123
35  SwiftUI                                0x10acc2eda 0x109c7f000 + 17055450
36  SwiftUI                                0x10acc2d93 0x109c7f000 + 17055123
37  SwiftUI                                0x10a9630d7 0x109c7f000 + 13517015
38  ShieldUp                               0x1015f1d2e static ShieldUpApp.$main() + 30
39  ShieldUp                               0x1015f1df9 main + 9 (ShieldUpApp.swift:12)
40  dyld_sim                               0x1017783e0 start_sim + 10
41  dyld                                   0x109b85418 start + 1896

修复方案 #

问题根源是Xcode Preview的沙箱环境禁止访问/dev/null。修改内存存储的配置方式，直接创建内存型持久化存储描述即可：

替换Persistence.swift中inMemory分支的代码：

if inMemory {
    let description = NSPersistentStoreDescription()
    description.type = NSInMemoryStoreType
    container.persistentStoreDescriptions = [description]
}

该方式会创建纯粹的内存CoreData存储，完全避开沙箱路径限制，同时保留原有预览数据生成逻辑。

内容的提问来源于stack exchange，提问作者niskah-media