我是iOS开发的新手，我目前正在从事一个涉及待办事项列表的项目，该列表在CoreData中存储"事件"的实体，以便我能够从这些实体请求数据并在视图中呈现数据。
当我通过点击按钮添加新事件时，出现错误
2020-05-23 20:10:19.478272-0700 simple[47194:7716218] [error] error: SQLCore dispatchRequest: exception handling request: <NSSQLFetchRequestContext: 0x600000af88c0> , keypath index not found in entity <NSSQLEntity Event id=1> with userInfo of (null)
CoreData: error: SQLCore dispatchRequest: exception handling request: <NSSQLFetchRequestContext: 0x600000af88c0> , keypath index not found in entity <NSSQLEntity Event id=1> with userInfo of (null)
2020-05-23 20:10:19.488151-0700 simple[47194:7716218] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'keypath index not found in entity <NSSQLEntity Event id=1>'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff23e3cf0e __exceptionPreprocess + 350
1 libobjc.A.dylib 0x00007fff50ba89b2 objc_exception_throw + 48
2 CoreData 0x00007fff23b0a226 -[NSSQLGenerator newSQLStatementForFetchRequest:ignoreInheritance:countOnly:nestingLevel:nestIsWhereScoped:requestContext:] + 0
3 CoreData 0x00007fff23b149f1 -[NSSQLiteAdapter _statementForFetchRequestContext:ignoreInheritance:countOnly:nestingLevel:] + 122
4 CoreData 0x00007fff239c76a7 -[NSSQLiteAdapter newSelectStatementWithFetchRequestContext:ignoreInheritance:] + 107
5 CoreData 0x00007fff23b67583 -[NSSQLFetchRequestContext _createStatement] + 67
6 CoreData 0x00007fff23b6752d -[NSSQLFetchRequestContext fetchStatement] + 142
7 CoreData 0x00007fff23b6837e -[NSSQLFetchRequestContext executeRequestCore:] + 33
8 CoreData 0x00007fff23bd8291 -[NSSQLStoreRequestContext executeRequestUsingConnection:] + 407
9 CoreData 0x00007fff23bab7c8 __52-[NSSQLDefaultConnectionManager handleStoreRequest:]_block_invoke + 56
10 CoreData 0x00007fff23b1fb85 __37-[NSSQLiteConnection performAndWait:]_block_invoke + 28
11 libdispatch.dylib 0x000000010ea5fe8e _dispatch_client_callout + 8
12 libdispatch.dylib 0x000000010ea6eae2 _dispatch_lane_barrier_sync_invoke_and_complete + 132
13 CoreData 0x00007fff23b1fa6b -[NSSQLiteConnection performAndWait:] + 145
14 CoreData 0x00007fff23bab6dd -[NSSQLDefaultConnectionManager handleStoreRequest:] + 284
15 CoreData 0x00007fff23bb1f0f -[NSSQLCoreDispatchManager routeStoreRequest:] + 283
16 CoreData 0x00007fff23af0006 -[NSSQLCore dispatchRequest:withRetries:] + 161
17 CoreData 0x00007fff23aeb69f -[NSSQLCore processFetchRequest:inContext:] + 88
18 CoreData 0x00007fff239c7069 -[NSSQLCore executeRequest:withContext:error:] + 1022
19 CoreData 0x00007fff23acb68c __65-[NSPersistentStoreCoordinator executeRequest:withContext:error:]_block_invoke.769 + 3179
20 CoreData 0x00007fff23ac3c23 -[NSPersistentStoreCoordinator _routeHeavyweightBlock:] + 233
21 CoreData 0x00007fff239c6670 -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 1486
22 CoreData 0x00007fff239c4a54 -[NSManagedObjectContext executeFetchRequest:error:] + 899
23 CoreData 0x00007fff23b75277 __43-[NSFetchedResultsController performFetch:]_block_invoke + 327
24 CoreData 0x00007fff23ad7ea1 gutsOfBlockToNSPersistentStoreCoordinatorPerform + 177
25 libdispatch.dylib 0x000000010ea5fe8e _dispatch_client_callout + 8
26 libdispatch.dylib 0x000000010ea6eae2 _dispatch_lane_barrier_sync_invoke_and_complete + 132
27 CoreData 0x00007fff23ac361e -[NSPersistentStoreCoordinator performBlockAndWait:] + 173
28 CoreData 0x00007fff23a0238d developerSubmittedBlockToNSManagedObjectContextPerform + 154
29 CoreData 0x00007fff23a02274 -[NSManagedObjectContext performBlockAndWait:] + 197
30 CoreData 0x00007fff23b7550b -[NSFetchedResultsController _recursivePerformBlockAndWait:withContext:] + 144
31 CoreData 0x00007fff23b75033 -[NSFetchedResultsController performFetch:] + 254
32 SwiftUI 0x00007fff2c8a74b9 $s7SwiftUI12FetchRequestV6updateyyF + 4105
33 SwiftUI 0x00007fff2c6a7088 $s7SwiftUI26EmbeddedDynamicPropertyBox33_49D2A32E637CD497C6DE29B8E060A506LLV6update8property7context5phaseSbxz_14AttributeGraph0T7ContextVyAA04VoidT0VGAA01_U6InputsV5PhaseVtF + 24
34 SwiftUI 0x00007fff2c8d5bba $s7SwiftUI9BoxVTable33_68550FF604D39F05971FE35A26EE75B0LLC6update3ptr8property7context5phaseSbSv_Sv14AttributeGraph0Q7ContextVyAA04VoidQ0VGAA01_R6InputsV5PhaseVtFZ + 202
35 SwiftUI 0x00007fff2c8d4f32 $s7SwiftUI22_DynamicPropertyBufferV6update9container7context5phaseSbSv_14AttributeGraph0J7ContextVyAA04VoidJ0VGAA01_K6InputsV5PhaseVtF + 146
36 SwiftUI 0x00007fff2c41d88f $s7SwiftUI19DynamicPropertyBody33_9F92ACD17B554E8AB7D29ABB1E796415LLV6update7contexty14AttributeGraph0P7ContextVyADyxGGz_tF + 479
37 SwiftUI 0x00007fff2c41e2f0 $s7SwiftUI19DynamicPropertyBody33_9F92ACD17B554E8AB7D29ABB1E796415LLVyxG14AttributeGraph07UntypedN0AafGP7_update_5graph9attributeySv_So10AGGraphRefaSo11AGAttributeatFZTW + 32
38 AttributeGraph 0x00007fff2fc78309 $sTA + 25
39 AttributeGraph 0x00007fff2fc60d3d _ZN2AG5Graph11UpdateStack6updateEv + 455
40 AttributeGraph 0x00007fff2fc6124b _ZN2AG5Graph16update_attributeEjb + 373
41 AttributeGraph 0x00007fff2fc65d53 _ZN2AG8Subgraph6updateEj + 729
42 SwiftUI 0x00007fff2c5359e0 $s7SwiftUI9ViewGraphC14runTransaction33_D63C4EB7F2B205694B6515509E76E98BLL2inySo10AGGraphRefa_tF + 224
43 SwiftUI 0x00007fff2c535db7 $s7SwiftUI9ViewGraphC13updateOutputs2atyAA4TimeV_tFSb5prefs_Sb9idealSizeAC0F0V7outputstSo10AGGraphRefaXEfU_ + 103
44 SwiftUI 0x00007fff2c535a9d $s7SwiftUI9ViewGraphC13updateOutputs2atyAA4TimeV_tF + 125
45 SwiftUI 0x00007fff2c81a7db $s7SwiftUI16ViewRendererHostPAAE6render8interval17updateDisplayListySd_SbtFyyXEfU_yyXEfU_ + 811
46 SwiftUI 0x00007fff2c819c33 $s7SwiftUI16ViewRendererHostPAAE6render8interval17updateDisplayListySd_SbtFyyXEfU_ + 547
47 SwiftUI 0x00007fff2c80f785 $s7SwiftUI16ViewRendererHostPAAE6render8interval17updateDisplayListySd_SbtF + 373
48 SwiftUI 0x00007fff2c96f9e2 $s7SwiftUI14_UIHostingViewC14layoutSubviewsyyF + 226
49 SwiftUI 0x00007fff2c96fa05 $s7SwiftUI14_UIHostingViewC14layoutSubviewsyyFTo + 21
50 UIKitCore 0x00007fff49193678 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2478
51 QuartzCore 0x00007fff2b4c6398 -[CALayer layoutSublayers] + 255
52 QuartzCore 0x00007fff2b4cc523 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 523
53 QuartzCore 0x00007fff2b4d7bba _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 80
54 QuartzCore 0x00007fff2b420c04 _ZN2CA7Context18commit_transactionEPNS_11TransactionEd + 324
55 QuartzCore 0x00007fff2b4545ef _ZN2CA11Transaction6commitEv + 649
56 UIKitCore 0x00007fff48ca3747 __34-[UIApplication _firstCommitBlock]_block_invoke_2 + 81
57 CoreFoundation 0x00007fff23da0b5c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
58 CoreFoundation 0x00007fff23da0253 __CFRunLoopDoBlocks + 195
59 CoreFoundation 0x00007fff23d9b043 __CFRunLoopRun + 995
60 CoreFoundation 0x00007fff23d9a944 CFRunLoopRunSpecific + 404
61 GraphicsServices 0x00007fff38ba6c1a GSEventRunModal + 139
62 UIKitCore 0x00007fff48c8b9ec UIApplicationMain + 1605
63 simple 0x000000010e7d222b main + 75
64 libdyld.dylib 0x00007fff51a231fd start + 1
65 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
我之前尝试将实体模块分配给当前产品模块，这解决了我之前遇到的问题。实体具有名称属性：字符串？并创建于：日期？
事件实体
import Foundation
import CoreData
public class Event:NSManagedObject,Identifiable {
@NSManaged public var name: String?
@NSManaged public var createdAt: Date?
}
extension Event {
static func getAllEvents() -> NSFetchRequest<Event> {
let request: NSFetchRequest<Event> = NSFetchRequest<Event>(entityName: "Event")
let sortDescriptor = NSSortDescriptor(key: "index", ascending:true)
request.sortDescriptors = [sortDescriptor]
return request
}
}
主视图
import CoreData
import SwiftUI
struct ContentView: View {
@Environment(.managedObjectContext) var managedObjectContext
@FetchRequest(fetchRequest: Event.getAllEvents()) var Events:FetchedResults<Event>
@State private var newEvent = ""
var body: some View {
NavigationView {
ScrollView {
Section(header: Text("What's Next?")) {
HStack {
TextField("New item,", text: self.$newEvent)
Button(action: {
let toDoItem = Event(context: self.managedObjectContext)
toDoItem.name = self.newEvent
toDoItem.createdAt = Date()
do{
try self.managedObjectContext.save()
} catch {
print(error)
}
self.newEvent = ""
}){
Image(systemName: "plus.circle.fill")
.foregroundColor(.green)
.imageScale(.large)
}
}
.padding()
}
}
.navigationBarTitle("name")
.navigationBarItems(trailing: EditButton())
}
}
}
您的实体没有">index"属性。您需要将">索引"属性更改为实体的属性之一。
let sortDescriptor = NSSortDescriptor(key: "attribute_name", ascending:true)
显然，您的实体有两个属性：name和createdAt。
let sortDescriptor = NSSortDescriptor(key: "index", ascending:true)
这就是问题所在。您正在尝试按index属性对提取结果进行排序，但您的实体Event没有此属性。您可以将其更改为
let sortDescriptor = NSSortDescriptor(key: "createdAt", ascending:true)