我正在将fetchRequestTemplate与NSPredicate一起使用以获取数据。我在以下代码段上看到“线程1：信号SIGABRT”：
fetchRequest.predicate = NSPredicate(format: "userID == %@", userID)
这是问题的完整说明：
2019-01-18 16:36:54.084567+0300 Chat[62769:8009479] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Can't modify a named fetch request in an immutable model.'
*** First throw call stack:
(
0 CoreFoundation 0x0000000107e811bb __exceptionPreprocess + 331
1 libobjc.A.dylib 0x0000000106e73735 objc_exception_throw + 48
2 CoreData 0x00000001077c7217 -[NSFetchRequest(_NSInternalMethods) _throwIfNotEditable] + 71
3 CoreData 0x00000001077c725e -[NSFetchRequest setPredicate:] + 30
4 Chat 0x00000001064d2db7 $S4Chat7MessageC11getMessages3for2inSayACGSgSS_So22NSManagedObjectContextCtFZ
+ 871
5 Chat 0x00000001064d2430 $S4Chat14StorageManagerC12readMessages3forSayAA12MessageModelCGSS_tF + 336
6 Chat 0x00000001064abfa9 $S4Chat20CommunicationManagerCACycfc + 2553
7 Chat 0x00000001064a8130 $S4Chat20CommunicationManagerCACycfC + 64
8 Chat 0x00000001064a80dc globalinit_33_C5FFB30340A1F300E36AFF644D48A8DA_func0 + 28
9 libdispatch.dylib 0x000000010a30a602 _dispatch_client_callout + 8
10 libdispatch.dylib 0x000000010a30c0c4 _dispatch_once_callout + 66
11 libswiftCore.dylib 0x0000000108676ea9 swift_once + 25
12 Chat 0x00000001064a81b4 $S4Chat20CommunicationManagerC06sharedbC0ACvau + 36
13 Chat 0x00000001064d599f $S4Chat11AppDelegateC11application_29didFinishLaunchingWithOptionsSbSo13UIApplicationC_SDySo0j6LaunchI3KeyaypGSgtF
+ 159
14 Chat 0x00000001064d5ac4 $S4Chat11AppDelegateC11application_29didFinishLaunchingWithOptionsSbSo13UIApplicationC_SDySo0j6LaunchI3KeyaypGSgtFTo
+ 228
15 UIKitCore 0x000000010bd02bde -[UIApplication _handleDelegateCallbacksWithOptions:isSuspended:restoreState:] + 280
16 UIKitCore 0x000000010bd045cb -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 3979
17 UIKitCore 0x000000010bd09c2f -[UIApplication _runWithMainScene:transitionContext:completion:] + 1623
18 UIKitCore 0x000000010b5284e9 __111-[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:]_block_invoke
+ 866
19 UIKitCore 0x000000010b53129c +[_UICanvas _enqueuePostSettingUpdateTransactionBlock:] + 153
20 UIKitCore 0x000000010b528126 -[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:] + 233
21 UIKitCore 0x000000010b528ae0 -[__UICanvasLifecycleMonitor_Compatability activateEventsOnly:withContext:completion:] + 1085
22 UIKitCore 0x000000010b526cb5 __82-[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:]_block_invoke
+ 795
23 UIKitCore 0x000000010b52695f -[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:] + 435
24 UIKitCore 0x000000010b52ba90 __125-[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:]_block_invoke
+ 584
25 UIKitCore 0x000000010b52c80e _performActionsWithDelayForTransitionContext + 100
26 UIKitCore 0x000000010b52b7ef -[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:]
+ 221
27 UIKitCore 0x000000010b53093a -[_UICanvas scene:didUpdateWithDiff:transitionContext:completion:] + 392
28 UIKitCore 0x000000010bd0844e -[UIApplication workspace:didCreateScene:withTransitionContext:completion:] + 515
29 UIKitCore 0x000000010b8acd09 -[UIApplicationSceneClientAgent scene:didInitializeWithEvent:completion:] + 357
30 FrontBoardServices 0x00000001143e82da -[FBSSceneImpl _didCreateWithTransitionContext:completion:] + 448
31 FrontBoardServices 0x00000001143f3443 __56-[FBSWorkspace client:handleCreateScene:withCompletion:]_block_invoke_2 + 271
32 FrontBoardServices 0x00000001143f2b3a __40-[FBSWorkspace _performDelegateCallOut:]_block_invoke + 53
33 libdispatch.dylib 0x000000010a30a602 _dispatch_client_callout + 8
34 libdispatch.dylib 0x000000010a30db78 _dispatch_block_invoke_direct + 301
35 FrontBoardServices 0x0000000114427ba8 __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 30
36 FrontBoardServices 0x0000000114427860 -[FBSSerialQueue _performNext] + 457
37 FrontBoardServices 0x0000000114427e40 -[FBSSerialQueue _performNextFromRunLoopSource] + 45
38 CoreFoundation 0x0000000107de6721 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
39 CoreFoundation 0x0000000107de5f93 __CFRunLoopDoSources0 + 243
40 CoreFoundation 0x0000000107de063f __CFRunLoopRun + 1263
41 CoreFoundation 0x0000000107ddfe11 CFRunLoopRunSpecific + 625
42 GraphicsServices 0x00000001114271dd GSEventRunModal + 62
43 UIKitCore 0x000000010bd0b81d UIApplicationMain + 140
44 Chat 0x00000001064d7037 main + 71
45 libdyld.dylib 0x000000010a380575 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)