At some point during the development of my SwiftUI app the canvas preview stopped loading. The app uses CoreData, and the crash log suggests issues with the persistence function. The app continues to work as expected on the device and using the simulator.
Top part of the crash log from preview:
Path: /Users/USER/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Bundle/Application/0011D911-75A5-4D79-AFA2-34BA2CB9E805/Training.app/Training
Identifier: Training
Version: 1.5 (11)
Code Type: X86-64 (Native)
Parent Process: launchd_sim [80779]
Responsible: SimulatorTrampoline [984]
User ID: 501
Date/Time: 2021-08-17 16:55:41.451 +0100
OS Version: macOS 11.5 (20G71)
Report Version: 12
Bridge OS Version: 3.0 (14Y908)
Anonymous UUID: A9FE029F-99BA-7511-2780-E515C2BA21E9
Sleep/Wake UUID: EA1649DE-D2A1-438F-8B86-9C8D63032F7F
Time Awake Since Boot: 160000 seconds
Time Since Wake: 11000 seconds
System Integrity Protection: enabled
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_BAD_INSTRUCTION (SIGILL)
Exception Codes: 0x0000000000000001, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY
Termination Signal: Illegal instruction: 4
Termination Reason: Namespace SIGNAL, Code 0x4
Terminating Process: exc handler [81046]
Application Specific Information:
Training/Persistence.swift:17: Fatal error: Unresolved error Error Domain=NSCocoaErrorDomain Code=134110 "An error occurred during persistent store migration." UserInfo={sourceURL=file:///Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator%20Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application%20Support/Training.sqlite, reason=Cannot migrate store in-place: I/O error for database at /Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application Support/Training.sqlite. SQLite error code:1, 'no such table: ZPROGRAMS', destinationURL=file:///Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator%20Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application%20Support/Training.sqlite, NSUnderlyingError=0x6000016b1200 {Error Domain=NSCocoaErrorDomain Code=134110 "An error occurred during persistent store migration." UserInfo={NSSQLiteErrorDomain=1, NSFilePath=/Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application Support/Training.sqlite, NSUnderlyingException=I/O error for database at /Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application Support/Training.sqlite. SQLite error code:1, 'no such table: ZPROGRAMS', reason=I/O error for database at /Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application Support/Training.sqlite. SQLite error code:1, 'no such table: ZPROGRAMS'}}}, ["reason": Cannot migrate store in-place: I/O error for database at /Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application Support/Training.sqlite. SQLite error code:1, 'no such table: ZPROGRAMS', "NSUnderlyingError": Error Domain=NSCocoaErrorDomain Code=134110 "An error occurred during persistent store migration." UserInfo={NSSQLiteErrorDomain=1, NSFilePath=/Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application Support/Training.sqlite, NSUnderlyingException=I/O error for database at /Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application Support/Training.sqlite. SQLite error code:1, 'no such table: ZPROGRAMS', reason=I/O error for database at /Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application Support/Training.sqlite. SQLite error code:1, 'no such table: ZPROGRAMS'}, "sourceURL": file:///Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator%20Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application%20Support/Training.sqlite, "destinationURL": file:///Users/liamday/Library/Developer/Xcode/UserData/Previews/Simulator%20Devices/836D94C3-1BF9-40BD-88EA-85DDF55F71E0/data/Containers/Data/Application/723C3942-DBEE-4A0E-BBBE-5F3B7F5F01A1/Library/Application%20Support/Training.sqlite]
CoreSimulator 757.5 - Device: iPhone 12 Pro (836D94C3-1BF9-40BD-88EA-85DDF55F71E0) - Runtime: iOS 14.5 (18E182) - DeviceType: iPhone 12 Pro
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 libswiftCore.dylib 0x00007fff2f07cd1e _assertionFailure(_:_:file:line:flags:) + 1742
1 co.uk.LiamDay.Training 0x0000000105d3266a closure #1 in PersistenceController.init(inMemory:) + 890 (Persistence.swift:17)
2 co.uk.LiamDay.Training 0x0000000105d326fb thunk for @escaping @callee_guaranteed (@guaranteed NSPersistentStoreDescription, @guaranteed Error?) -> () + 139
3 CoreData 0x00007fff251a7838 -[NSPersistentStoreCoordinator _doAddPersistentStoreWithDescription:privateCopy:completeOnMainThread:withHandler:] + 978
4 CoreData 0x00007fff251a7c3a -[NSPersistentStoreCoordinator addPersistentStoreWithDescription:completionHandler:] + 236
5 CoreData 0x00007fff2514b01b -[NSPersistentContainer _loadStoreDescriptions:withCompletionHandler:] + 272
6 CoreData 0x00007fff2514aee4 -[NSPersistentContainer loadPersistentStoresWithCompletionHandler:] + 398
7 co.uk.LiamDay.Training 0x0000000105d32144 PersistenceController.init(inMemory:) + 1060 (Persistence.swift:15)
8 co.uk.LiamDay.Training 0x0000000105d31d01 one-time initialization function for shared + 17 (Persistence.swift:6)
9 libdispatch.dylib 0x00007fff201078df _dispatch_client_callout + 8
10 libdispatch.dylib 0x00007fff20108b16 _dispatch_once_callout + 20
11 libswiftCore.dylib 0x00007fff2f3a059a swift_once + 26
12 co.uk.LiamDay.Training 0x0000000105d32234 PersistenceController.shared.unsafeMutableAddressor + 52 (Persistence.swift:6)
13 co.uk.LiamDay.Training 0x0000000105e73ba0 TrainingApp.init() + 80 (TrainingApp.swift:12)
14 co.uk.LiamDay.Training 0x0000000105e73ce1 protocol witness for App.init() in conformance TrainingApp + 17
15 com.apple.SwiftUI 0x00007fff562e5376 static App.main() + 47
16 co.uk.LiamDay.Training 0x0000000105e73c6e static TrainingApp.$main() + 78 (TrainingApp.swift:10)
17 co.uk.LiamDay.Training 0x0000000105e73d04 main + 20
18 libdyld.dylib 0x00007fff2025abbd start + 1
Thread 1:
0 libsystem_pthread.dylib 0x00007fff6033f420 start_wqthread + 0
Thread 2:
0 libsystem_pthread.dylib 0x00007fff6033f420 start_wqthread + 0
Thread 0 crashed with X86 Thread State (64-bit):
rax: 0x0000000200000003 rbx: 0x0000000106005a90 rcx: 0xfffffffe00000000 rdx: 0x0000000000000003
rdi: 0x00007fe683033208 rsi: 0x0000000000000103 rbp: 0x00007ffee9ed0430 rsp: 0x00007ffee9ed0390
r8: 0x0000000106868a00 r9: 0x00000001068603e0 r10: 0x0000000000000040 r11: 0x000000000000003b
r12: 0x0000000000000f30 r13: 0x00007ffee9ed0350 r14: 0x000000000000000b r15: 0x00007ffee9ed0390
rip: 0x00007fff2f07cd1e rfl: 0x0000000000010246 cr2: 0x00007fff2067e4ee
Logical CPU: 1
Error Code: 0x00000000
Trap Number: 6
Thread 0 instruction stream:
fe fe fe fe fe fe 00 b9-20 00 00 00 45 85 c0 74 ........ ...E..t
07 41 0f bd c8 83 f1 1f-c1 e9 03 be 04 00 00 00 .A..............
48 29 ce 8d 0c f5 00 00-00 00 48 c7 c2 ff ff ff H)........H.....
ff 48 d3 e2 48 f7 d2 44-89 c1 48 01 c1 48 21 d1 .H..H..D..H..H!.
48 89 4d b8 48 8d 15 77-15 00 00 48 8d 7d b8 e8 H.M.H..w...H.}..
1e 35 2d 00 4c 89 fc 48-8b 7d d0 e8 12 df 32 00 .5-.L..H.}....2.
[0f]0b 55 48 89 e5 31 c0-5d c3 0f 1f 84 00 00 00 ..UH..1.]....... <==
00 00 55 48 89 e5 41 57-41 56 41 55 41 54 53 50 ..UH..AWAVAUATSP
4d 89 cc 45 89 c6 49 89-cf 48 89 d3 49 89 f5 ff M..E..I..H..I...
d7 49 89 d0 48 8d 3d bb-14 38 00 be 0b 00 00 00 .I..H.=..8......
ba 02 00 00 00 48 89 c1-49 89 d9 6a 00 41 54 41 .....H..I..j.ATA
56 41 57 e8 da f8 ff ff-48 83 c4 20 0f 0b 0f 1f VAW.....H.. ....
Thread 0 last branch register state not available.
This is my Persistence.swift file:
import CloudKit
struct PersistenceController {
//MARK: - 1. PERSISTENCE CONTROLLER
static let shared = PersistenceController()
//MARK: - 2. PERSISTENT CONTAINER
let container: NSPersistentContainer
//MARK: - 3. INIT (load the persistent store)
init(inMemory: Bool = false) {
container = NSPersistentContainer(name: "Training")
if inMemory {
container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
}
container.loadPersistentStores(completionHandler: { (storeDescription, error) in
if let error = error as NSError? {
fatalError("Unresolved error \(error), \(error.userInfo)")
}
})
}
//MARK: - 4. PREVIEW
static var preview: PersistenceController = {
let result = PersistenceController(inMemory: true)
let viewContext = result.container.viewContext
let plannedExercise1 = PlannedWorkouts(context: viewContext)
plannedExercise1.dateCreated = Date()
plannedExercise1.dateOfWorkout = Date()
plannedExercise1.duration = 3600.00
plannedExercise1.totalDistanceUnit = "meters"
plannedExercise1.totalDistanceDoubleValue = 5000.0
plannedExercise1.totalEnergyBurnedUnit = "KCal"
plannedExercise1.totalEnergyBurnedDoubleValue = 500.0
plannedExercise1.workoutActivityType = 32
plannedExercise1.id = UUID()
let plannedExercise2 = PlannedWorkouts(context: viewContext)
plannedExercise2.dateCreated = K.init().EndOfWeek(weeksSinceAnchorDate: 1)
plannedExercise2.dateOfWorkout = Date()
plannedExercise2.duration = 3600.00
plannedExercise2.totalDistanceUnit = "meters"
plannedExercise2.totalDistanceDoubleValue = 5000.0
plannedExercise2.totalEnergyBurnedUnit = "KCal"
plannedExercise2.totalEnergyBurnedDoubleValue = 500.0
plannedExercise2.workoutActivityType = 35
plannedExercise2.id = UUID()
let newStatisticChartView = ChartView(context: viewContext)
newStatisticChartView.id = UUID()
newStatisticChartView.chartViewRawValue = "dailyTrainingImpactChartView"
let newGoalView = GoalViews(context: viewContext)
newGoalView.startDate = K.init().EndOfWeek(weeksSinceAnchorDate: 1)
newGoalView.endDate = K.init().EndOfWeek(weeksSinceAnchorDate: 2)
newGoalView.id = UUID()
newGoalView.totalDistanceUnit = "meters"
newGoalView.totalDistanceDoubleValue = 30000
newGoalView.workoutActivityType = Int16(32)
let newProgram = Programs(context: viewContext)
let newProgrammedWorkout = ProgrammedWorkouts(context: viewContext)
let newPlannedProgram = PlannedPrograms(context: viewContext)
do {
try viewContext.save()
} catch {
let nsError = error as NSError
fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
}
return result
}()
}
I have restarted Xcode and cleared the derived data. What should I try next? Or is this the limitations of the previewer with SwiftUI for complex app builds?
The answer to your question is in the long string of the debug output. Simply put, there is a problem with updating the database Training.sqlite which is created automatically by the persistent container framework.
Try deleting these folders / files manually. You can find the full path in the error message.
Also, as pointed out by other posters, it is advisable to use PersistentController.preview when constructing the preview database. It will then always be created from scratch in memory.