谁能提供有关调试此核心数据迁移问题的建议？
Can anyone offer advice on debugging this core data migration issue?
我刚刚执行了重量级核心迁移 - 我不确定重量级和轻量级之间的界线在哪里 - 这个涉及 5 个映射和 1 个自定义 class。我当然可以提供其中任何一个。在我看来，它可能已经成功了——我的应用程序正在启动，它一直到 viewDidLoad——只有当它试图执行 fetchRequest 时才会崩溃。如果能帮助调试以下错误消息，我将不胜感激。我有一些问题：
- 迁移成功了吗？有任何方法可以知道它是否有效，这是否是我的提取请求的问题，或者数据是否以某种方式损坏，或者它是否根本无法工作。检查这个的最好方法是什么？
- 为什么 SQL 中有这么多问号 - 是否意味着迁移不正常？
- Z是什么？所有属性似乎都以 Z 开头 - "WHERE t0.ZNOTES IS NOT NULL for instance"
- 什么是 NSSymbolicExpression？它会发生在核心数据迁移的什么地方。我知道它以某种方式试图找到该对象的长度，而该对象没有该实例方法。这是否意味着它假定迁移已完成，例如尚未完成？
如能提供有关上述任何内容的信息，我们将不胜感激 - 包括可在何处找到更多 this/read 的资源。我一直在尝试了解苹果文档中的迁移，但遇到了麻烦。一直在努力...有什么帮助，谢谢:)
CoreData: annotation: Connecting to sqlite database file at "/Users/alexmarshall/Library/Developer/CoreSimulator/Devices/252E29AE-83C0-4063-8000-C4302854B529/data/Containers/Data/Application/2AC9D1D5-AA70-4236-B9C5-E5C711C4AF28/Library/Application Support/SweatNetOffline.sqlite"
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: pragma recursive_triggers=1
CoreData: sql: pragma journal_mode=wal
CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA
CoreData: annotation: Connecting to sqlite database file at "/Users/alexmarshall/Library/Developer/CoreSimulator/Devices/252E29AE-83C0-4063-8000-C4302854B529/data/Containers/Data/Application/2AC9D1D5-AA70-4236-B9C5-E5C711C4AF28/Library/Application Support/SweatNetOffline.sqlite"
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'ACHANGE'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'ATRANSACTIONSTRING'
CoreData: annotation: Connecting to sqlite database file at "/Users/alexmarshall/Library/Developer/CoreSimulator/Devices/252E29AE-83C0-4063-8000-C4302854B529/data/Containers/Data/Application/2AC9D1D5-AA70-4236-B9C5-E5C711C4AF28/Library/Application Support/.SweatNetOffline.sqlite.migrationdestination_41b5a6b5c6e848c462a8480cd24caef3"
CoreData: annotation: creating schema.
CoreData: sql: pragma page_size=4096
CoreData: sql: pragma auto_vacuum=2
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: CREATE TABLE ZRECORD ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZRECORDTYPE INTEGER, ZSKILL INTEGER, ZTIMESTAMP TIMESTAMP, ZIMAGEFILENAME VARCHAR, ZTEXT VARCHAR, ZTHUMBNAILFILENAME VARCHAR, ZVIDEOFILENAME VARCHAR )
CoreData: sql: CREATE TABLE ZSKILL ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZMETADATA INTEGER, ZNAME VARCHAR )
CoreData: sql: CREATE TABLE ZSKILLMETADATA ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZDIFFICULTY INTEGER, ZISACTIVE INTEGER, ZSKILL INTEGER, ZLATESTUPDATE TIMESTAMP, ZSECTIONIDENTIFIER VARCHAR, ZTHUMBNAIL BLOB )
CoreData: sql: CREATE INDEX IF NOT EXISTS ZRECORD_ZSKILL_INDEX ON ZRECORD (ZSKILL)
CoreData: sql: CREATE INDEX IF NOT EXISTS ZRECORD_Z_ENT_INDEX ON ZRECORD (Z_ENT)
CoreData: sql: CREATE INDEX IF NOT EXISTS ZSKILL_ZMETADATA_INDEX ON ZSKILL (ZMETADATA)
CoreData: sql: CREATE INDEX IF NOT EXISTS ZSKILLMETADATA_ZSKILL_INDEX ON ZSKILLMETADATA (ZSKILL)
CoreData: annotation: Creating primary key table.
CoreData: sql: CREATE TABLE Z_PRIMARYKEY (Z_ENT INTEGER PRIMARY KEY, Z_NAME VARCHAR, Z_SUPER INTEGER, Z_MAX INTEGER)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(1, 'Record', 0, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(2, 'ImageRecord', 1, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(3, 'TextRecord', 1, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(4, 'VideoRecord', 1, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(5, 'Skill', 0, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(6, 'SkillMetaData', 0, 0)
CoreData: sql: CREATE TABLE Z_METADATA (Z_VERSION INTEGER PRIMARY KEY, Z_UUID VARCHAR(255), Z_PLIST BLOB)
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: DELETE FROM Z_METADATA WHERE Z_VERSION = ?
CoreData: sql: INSERT INTO Z_METADATA (Z_VERSION, Z_UUID, Z_PLIST) VALUES (?, ?, ?)
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_MODELCACHE'
CoreData: sql: CREATE TABLE Z_MODELCACHE (Z_CONTENT BLOB)
CoreData: sql: INSERT INTO Z_MODELCACHE (Z_CONTENT) VALUES (?)
CoreData: sql: COMMIT
CoreData: sql: pragma recursive_triggers=1
CoreData: sql: pragma journal_mode
CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_MODELCACHE'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'ACHANGE'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'ATRANSACTIONSTRING'
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: DELETE FROM Z_METADATA WHERE Z_VERSION = ?
CoreData: sql: INSERT INTO Z_METADATA (Z_VERSION, Z_UUID, Z_PLIST) VALUES (?, ?, ?)
CoreData: sql: COMMIT
CoreData: sql: pragma page_count
CoreData: annotation: sql execution time: 0.0002s
CoreData: sql: pragma freelist_count
CoreData: annotation: sql execution time: 0.0001s
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZLATESTUPDATE, t0.ZNAME, t0.ZUUID FROM ZTAG t0
CoreData: annotation: sql connection fetch time: 0.0004s
CoreData: annotation: total fetch execution time: 0.0008s for 1 rows.
CoreData: sql: SELECT t0.Z_ENT, t0.Z_PK, Z_FOK_1POSTS FROM ZPOST t0 JOIN Z_1TAGS t1 ON t0.Z_PK = t1.Z_1POSTS WHERE t1.Z_2TAGS = ?
CoreData: annotation: sql connection fetch time: 0.0005s
CoreData: annotation: total fetch execution time: 0.0006s for 1 rows.
CoreData: annotation: to-many relationship fault "posts" for objectID 0x9de26d27ef2a7aca <x-coredata://DDA9D961-398D-4C5C-8DAA-919F17139695/Tag/p1> fulfilled from database. Got 1 rows
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZISVIDEO, t0.ZMEDIAFILENAME, t0.ZNOTES, t0.ZPOSTIMAGE, t0.ZTIMESTAMP FROM ZPOST t0 WHERE t0.Z_PK = ?
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0002s for 1 rows.
CoreData: annotation: fault fulfilled from database for : 0x9de26d27ef2a7ac8 <x-coredata://DDA9D961-398D-4C5C-8DAA-919F17139695/Post/p1>
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: SELECT Z_MAX FROM Z_PRIMARYKEY WHERE Z_ENT = ?
CoreData: sql: UPDATE OR FAIL Z_PRIMARYKEY SET Z_MAX = ? WHERE Z_ENT = ? AND Z_MAX = ?
CoreData: sql: COMMIT
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: INSERT INTO ZSKILLMETADATA(Z_PK, Z_ENT, Z_OPT, ZSKILL, ZDIFFICULTY, ZISACTIVE, ZLATESTUPDATE, ZSECTIONIDENTIFIER, ZTHUMBNAIL) VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?)
CoreData: sql: COMMIT
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZISVIDEO, t0.ZMEDIAFILENAME, t0.ZNOTES, t0.ZPOSTIMAGE, t0.ZTIMESTAMP FROM ZPOST t0 WHERE t0.ZNOTES IS NOT NULL
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0002s for 0 rows.
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZISVIDEO, t0.ZMEDIAFILENAME, t0.ZNOTES, t0.ZPOSTIMAGE, t0.ZTIMESTAMP FROM ZPOST t0 WHERE ( t0.ZISVIDEO IS NOT NULL AND t0.ZISVIDEO = ?)
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0002s for 1 rows.
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: COMMIT
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: INSERT INTO ZRECORD(Z_PK, Z_ENT, Z_OPT, ZSKILL, ZRECORDTYPE, ZTIMESTAMP, ZIMAGEFILENAME) VALUES(?, ?, ?, ?, ?, ?, ?)
CoreData: sql: COMMIT
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZISVIDEO, t0.ZMEDIAFILENAME, t0.ZNOTES, t0.ZPOSTIMAGE, t0.ZTIMESTAMP FROM ZPOST t0 WHERE ( t0.ZISVIDEO IS NOT NULL AND t0.ZISVIDEO = ?)
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0002s for 0 rows.
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: UPDATE OR FAIL ZSKILLMETADATA SET Z_OPT = ? WHERE Z_PK = ? AND Z_OPT = ?
CoreData: sql: COMMIT
CoreData: sql: SELECT t0.Z_ENT, t0.Z_PK, Z_FOK_2TAGS FROM ZTAG t0 JOIN Z_1TAGS t1 ON t0.Z_PK = t1.Z_2TAGS WHERE t1.Z_1POSTS = ?
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0001s for 1 rows.
CoreData: annotation: to-many relationship fault "tags" for objectID 0x9de26d27ef2a7ac8 <x-coredata://DDA9D961-398D-4C5C-8DAA-919F17139695/Post/p1> fulfilled from database. Got 1 rows
2020-04-16 10:34:32.587088-0700 SweatNetOffline[33644:4324282] -[NSSymbolicExpression length]: unrecognized selector sent to instance 0x60000315f820
CoreData: annotation: Disconnecting from sqlite database.
CoreData: annotation: Disconnecting from sqlite database.
CoreData: annotation: Disconnecting from sqlite database.
2020-04-16 10:34:32.619490-0700 SweatNetOffline[33644:4324282] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSSymbolicExpression length]: unrecognized selector sent to instance 0x60000315f820'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff23c7127e __exceptionPreprocess + 350
1 libobjc.A.dylib 0x00007fff513fbb20 objc_exception_throw + 48
2 CoreFoundation 0x00007fff23c91fd4 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
3 CoreFoundation 0x00007fff23c75c4c ___forwarding___ + 1436
4 CoreFoundation 0x00007fff23c77f78 _CF_forwarding_prep_0 + 120
5 Foundation 0x00007fff257159b4 -[NSOrderedSet(NSKeyValueCoding) valueForKeyPath:] + 53
6 Foundation 0x00007fff257fea18 -[NSFunctionExpression expressionValueWithObject:context:] + 707
7 Foundation 0x00007fff257fe935 -[NSFunctionExpression expressionValueWithObject:context:] + 480
8 CoreData 0x00007fff238aa500 -[NSEntityMigrationPolicy createRelationshipsForDestinationInstance:entityMapping:manager:error:] + 1272
9 CoreData 0x00007fff238f5a98 -[NSMigrationManager(InternalMethods) _doSecondPassForMapping:error:] + 418
10 CoreData 0x00007fff238f6c00 -[NSMigrationManager(InternalMethods) _migrateStoreFromURL:type:options:withMappingModel:toDestinationURL:destinationType:destinationOptions:error:] + 2012
11 CoreData 0x00007fff238f3c9f -[NSMigrationManager migrateStoreFromURL:type:options:withMappingModel:toDestinationURL:destinationType:destinationOptions:error:] + 664
12 CoreData 0x00007fff239a5eab -[NSStoreMigrationPolicy(InternalMethods) migrateStoreAtURL:toURL:storeType:options:withManager:error:] + 254
13 CoreData 0x00007fff239a5466 -[NSStoreMigrationPolicy migrateStoreAtURL:withManager:metadata:options:error:] + 99
14 CoreData 0x00007fff239a6adf -[NSStoreMigrationPolicy(InternalMethods) _gatherDataAndPerformMigration:] + 2829
15 CoreData 0x00007fff238fc335 __91-[NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:]_block_invoke + 2469
16 CoreData 0x00007fff2390ceb9 gutsOfBlockToNSPersistentStoreCoordinatorPerform + 177
17 libdispatch.dylib 0x0000000110c5ed48 _dispatch_client_callout + 8
18 libdispatch.dylib 0x0000000110c6d9bf _dispatch_lane_barrier_sync_invoke_and_complete + 132
19 CoreData 0x00007fff238f88f9 _perform + 181
20 CoreData 0x00007fff237e9334 -[NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:] + 416
21 CoreData 0x00007fff238fb31b -[NSPersistentStoreCoordinator _doAddPersistentStoreWithDescription:privateCopy:completeOnMainThread:withHandler:] + 515
22 CoreData 0x00007fff238fb8ab -[NSPersistentStoreCoordinator addPersistentStoreWithDescription:completionHandler:] + 205
23 CoreData 0x00007fff238aef63 -[NSPersistentContainer _loadStoreDescriptons:withCompletionHandler:] + 272
24 CoreData 0x00007fff238aee2c -[NSPersistentContainer loadPersistentStoresWithCompletionHandler:] + 398
25 SweatNetOffline 0x000000010fa9dc05 $s15SweatNetOffline11AppDelegateC19persistentContainerSo012NSPersistentG0CvgAFyXEfU_ + 181
26 SweatNetOffline 0x000000010fa9da97 $s15SweatNetOffline11AppDelegateC19persistentContainerSo012NSPersistentG0Cvg + 375
27 SweatNetOffline 0x000000010fae8788 $s15SweatNetOffline19Home2ViewControllerC019skillFetchedResultsF033_A1FE4BA766270B7DD28F222CBF923E7DLLSo09NSFetchediF0CyAA13SkillMetaDataCGvgAJyXEfU_ + 360
28 SweatNetOffline 0x000000010fae5497 $s15SweatNetOffline19Home2ViewControllerC019skillFetchedResultsF033_A1FE4BA766270B7DD28F222CBF923E7DLLSo09NSFetchediF0CyAA13SkillMetaDataCGvg + 375
29 SweatNetOffline 0x000000010fae5771 $s15SweatNetOffline19Home2ViewControllerC11viewDidLoadyyF + 177
30 SweatNetOffline 0x000000010fae5c1b $s15SweatNetOffline19Home2ViewControllerC11viewDidLoadyyFTo + 43
31 UIKitCore 0x00007fff47a0ef01 -[UIViewController _sendViewDidLoadWithAppearanceProxyObjectTaggingEnabled] + 83
32 UIKitCore 0x00007fff47a13e5a -[UIViewController loadViewIfRequired] + 1084
33 UIKitCore 0x00007fff479781e4 -[UINavigationController _updateScrollViewFromViewController:toViewController:] + 160
34 UIKitCore 0x00007fff479784e8 -[UINavigationController _startTransition:fromViewController:toViewController:] + 144
35 UIKitCore 0x00007fff479793b6 -[UINavigationController _startDeferredTransitionIfNeeded:] + 868
36 UIKitCore 0x00007fff4797a721 -[UINavigationController __viewWillLayoutSubviews] + 150
37 UIKitCore 0x00007fff4795b553 -[UILayoutContainerView layoutSubviews] + 217
38 UIKitCore 0x00007fff485784bd -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2478
39 QuartzCore 0x00007fff2b131db1 -[CALayer layoutSublayers] + 255
40 QuartzCore 0x00007fff2b137fa3 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 517
41 QuartzCore 0x00007fff2b1438da _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 80
42 QuartzCore 0x00007fff2b08a848 _ZN2CA7Context18commit_transactionEPNS_11TransactionEd + 324
43 QuartzCore 0x00007fff2b0bfb51 _ZN2CA11Transaction6commitEv + 643
44 UIKitCore 0x00007fff480aa575 __34-[UIApplication _firstCommitBlock]_block_invoke_2 + 81
45 CoreFoundation 0x00007fff23bd429c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
46 CoreFoundation 0x00007fff23bd3a08 __CFRunLoopDoBlocks + 312
47 CoreFoundation 0x00007fff23bce894 __CFRunLoopRun + 1284
48 CoreFoundation 0x00007fff23bce066 CFRunLoopRunSpecific + 438
49 GraphicsServices 0x00007fff384c0bb0 GSEventRunModal + 65
50 UIKitCore 0x00007fff48092d4d UIApplicationMain + 1621
51 SweatNetOffline 0x000000010fa9ea7b main + 75
52 libdyld.dylib 0x00007fff5227ec25 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
- Did the migration work? Any way to know if it worked and if this is an issue with my fetch request or if somehow the data was corrupted or if it never worked at all. What is the best way to check this?
抛出异常时，我认为迁移仍在进行中。如果您查看调用堆栈，堆栈中似乎更早发生了与迁移相关的调用：
1 ... objc_exception_throw + 48
2 ... [NSObject(NSObject) doesNotRecognizeSelector:] + 132
3 ... ___forwarding___ + 1436
4 ... _CF_forwarding_prep_0 + 120
5 ... [NSOrderedSet(NSKeyValueCoding) valueForKeyPath:] + 53
6 ... [NSFunctionExpression expressionValueWithObject:context:] + 707
7 ... [NSFunctionExpression expressionValueWithObject:context:] + 480
8 ... [NSEntityMigrationPolicy createRelationshipsForDestinationInstance:entityMapping:manager:error:] + 1272
9 ... [NSMigrationManager(InternalMethods) _doSecondPassForMapping:error:] + 418
10 ... [NSMigrationManager(InternalMethods) _migrateStoreFromURL:type:options:withMappingModel:toDestinationURL:destinationType:destinationOptions:error:] + 2012
我不会假设迁移已完成，只是因为调用了您的 viewDidLoad 方法：迁移可能异步发生 - 这取决于您的 CoreData 堆栈的创建方式。
- Why are there so many question marks in the SQL - does the mean that the migration is not working properly?
这正是您使用 SQLDebug 时 CoreData 记录值的方式。他们没什么好担心的。
- What is Z? all of the attributes seem to start with Z - "WHERE t0.ZNOTES IS NOT NULL" for instance
当 CoreData 创建 SQLite 数据库时，从广义上讲，它会为每个实体创建一个 table，其中的列表示属性。 table 名称和列名称总是（至少根据我的经验）以 "Z" 为前缀。所以，再说一次，Zs 不用担心。
- What is an NSSymbolicExpression? Where would it occur in the core data migration. I understand that somehow its trying to find the length of this object, and the object doesn't have that instance method. Does that mean it is assuming the migration is completed when it hasn't been for instance?
我的猜测是您的迁移代码中存在指针不匹配问题：指向类似 NSString（确实响应 length）的指针实际上指向 NSSymbolicExpression 对象（它不响应该选择器）。如果 NSString 对象被释放（并释放），并且它占用的内存随后分配给 NSSymbolicExpression 对象，则可能会发生这种情况。
我该如何调试它？我会首先在您的迁移代码中放置一个断点，然后单步执行以尝试找到有问题的代码。您还可以尝试启用 Zombie 跟踪（当访问已释放对象使用的内存时会发出标记）。这超出了我在这里所能涵盖的范围：一些谷歌搜索应该会有所帮助。
我刚刚执行了重量级核心迁移 - 我不确定重量级和轻量级之间的界线在哪里 - 这个涉及 5 个映射和 1 个自定义 class。我当然可以提供其中任何一个。在我看来，它可能已经成功了——我的应用程序正在启动，它一直到 viewDidLoad——只有当它试图执行 fetchRequest 时才会崩溃。如果能帮助调试以下错误消息，我将不胜感激。我有一些问题：
- 迁移成功了吗？有任何方法可以知道它是否有效，这是否是我的提取请求的问题，或者数据是否以某种方式损坏，或者它是否根本无法工作。检查这个的最好方法是什么？
- 为什么 SQL 中有这么多问号 - 是否意味着迁移不正常？
- Z是什么？所有属性似乎都以 Z 开头 - "WHERE t0.ZNOTES IS NOT NULL for instance"
- 什么是 NSSymbolicExpression？它会发生在核心数据迁移的什么地方。我知道它以某种方式试图找到该对象的长度，而该对象没有该实例方法。这是否意味着它假定迁移已完成，例如尚未完成？
如能提供有关上述任何内容的信息，我们将不胜感激 - 包括可在何处找到更多 this/read 的资源。我一直在尝试了解苹果文档中的迁移，但遇到了麻烦。一直在努力...有什么帮助，谢谢:)
CoreData: annotation: Connecting to sqlite database file at "/Users/alexmarshall/Library/Developer/CoreSimulator/Devices/252E29AE-83C0-4063-8000-C4302854B529/data/Containers/Data/Application/2AC9D1D5-AA70-4236-B9C5-E5C711C4AF28/Library/Application Support/SweatNetOffline.sqlite"
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: pragma recursive_triggers=1
CoreData: sql: pragma journal_mode=wal
CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA
CoreData: annotation: Connecting to sqlite database file at "/Users/alexmarshall/Library/Developer/CoreSimulator/Devices/252E29AE-83C0-4063-8000-C4302854B529/data/Containers/Data/Application/2AC9D1D5-AA70-4236-B9C5-E5C711C4AF28/Library/Application Support/SweatNetOffline.sqlite"
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'ACHANGE'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'ATRANSACTIONSTRING'
CoreData: annotation: Connecting to sqlite database file at "/Users/alexmarshall/Library/Developer/CoreSimulator/Devices/252E29AE-83C0-4063-8000-C4302854B529/data/Containers/Data/Application/2AC9D1D5-AA70-4236-B9C5-E5C711C4AF28/Library/Application Support/.SweatNetOffline.sqlite.migrationdestination_41b5a6b5c6e848c462a8480cd24caef3"
CoreData: annotation: creating schema.
CoreData: sql: pragma page_size=4096
CoreData: sql: pragma auto_vacuum=2
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: CREATE TABLE ZRECORD ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZRECORDTYPE INTEGER, ZSKILL INTEGER, ZTIMESTAMP TIMESTAMP, ZIMAGEFILENAME VARCHAR, ZTEXT VARCHAR, ZTHUMBNAILFILENAME VARCHAR, ZVIDEOFILENAME VARCHAR )
CoreData: sql: CREATE TABLE ZSKILL ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZMETADATA INTEGER, ZNAME VARCHAR )
CoreData: sql: CREATE TABLE ZSKILLMETADATA ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZDIFFICULTY INTEGER, ZISACTIVE INTEGER, ZSKILL INTEGER, ZLATESTUPDATE TIMESTAMP, ZSECTIONIDENTIFIER VARCHAR, ZTHUMBNAIL BLOB )
CoreData: sql: CREATE INDEX IF NOT EXISTS ZRECORD_ZSKILL_INDEX ON ZRECORD (ZSKILL)
CoreData: sql: CREATE INDEX IF NOT EXISTS ZRECORD_Z_ENT_INDEX ON ZRECORD (Z_ENT)
CoreData: sql: CREATE INDEX IF NOT EXISTS ZSKILL_ZMETADATA_INDEX ON ZSKILL (ZMETADATA)
CoreData: sql: CREATE INDEX IF NOT EXISTS ZSKILLMETADATA_ZSKILL_INDEX ON ZSKILLMETADATA (ZSKILL)
CoreData: annotation: Creating primary key table.
CoreData: sql: CREATE TABLE Z_PRIMARYKEY (Z_ENT INTEGER PRIMARY KEY, Z_NAME VARCHAR, Z_SUPER INTEGER, Z_MAX INTEGER)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(1, 'Record', 0, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(2, 'ImageRecord', 1, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(3, 'TextRecord', 1, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(4, 'VideoRecord', 1, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(5, 'Skill', 0, 0)
CoreData: sql: INSERT INTO Z_PRIMARYKEY(Z_ENT, Z_NAME, Z_SUPER, Z_MAX) VALUES(6, 'SkillMetaData', 0, 0)
CoreData: sql: CREATE TABLE Z_METADATA (Z_VERSION INTEGER PRIMARY KEY, Z_UUID VARCHAR(255), Z_PLIST BLOB)
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: DELETE FROM Z_METADATA WHERE Z_VERSION = ?
CoreData: sql: INSERT INTO Z_METADATA (Z_VERSION, Z_UUID, Z_PLIST) VALUES (?, ?, ?)
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_MODELCACHE'
CoreData: sql: CREATE TABLE Z_MODELCACHE (Z_CONTENT BLOB)
CoreData: sql: INSERT INTO Z_MODELCACHE (Z_CONTENT) VALUES (?)
CoreData: sql: COMMIT
CoreData: sql: pragma recursive_triggers=1
CoreData: sql: pragma journal_mode
CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_MODELCACHE'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'ACHANGE'
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'ATRANSACTIONSTRING'
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: SELECT TBL_NAME FROM SQLITE_MASTER WHERE TBL_NAME = 'Z_METADATA'
CoreData: sql: DELETE FROM Z_METADATA WHERE Z_VERSION = ?
CoreData: sql: INSERT INTO Z_METADATA (Z_VERSION, Z_UUID, Z_PLIST) VALUES (?, ?, ?)
CoreData: sql: COMMIT
CoreData: sql: pragma page_count
CoreData: annotation: sql execution time: 0.0002s
CoreData: sql: pragma freelist_count
CoreData: annotation: sql execution time: 0.0001s
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZLATESTUPDATE, t0.ZNAME, t0.ZUUID FROM ZTAG t0
CoreData: annotation: sql connection fetch time: 0.0004s
CoreData: annotation: total fetch execution time: 0.0008s for 1 rows.
CoreData: sql: SELECT t0.Z_ENT, t0.Z_PK, Z_FOK_1POSTS FROM ZPOST t0 JOIN Z_1TAGS t1 ON t0.Z_PK = t1.Z_1POSTS WHERE t1.Z_2TAGS = ?
CoreData: annotation: sql connection fetch time: 0.0005s
CoreData: annotation: total fetch execution time: 0.0006s for 1 rows.
CoreData: annotation: to-many relationship fault "posts" for objectID 0x9de26d27ef2a7aca <x-coredata://DDA9D961-398D-4C5C-8DAA-919F17139695/Tag/p1> fulfilled from database. Got 1 rows
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZISVIDEO, t0.ZMEDIAFILENAME, t0.ZNOTES, t0.ZPOSTIMAGE, t0.ZTIMESTAMP FROM ZPOST t0 WHERE t0.Z_PK = ?
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0002s for 1 rows.
CoreData: annotation: fault fulfilled from database for : 0x9de26d27ef2a7ac8 <x-coredata://DDA9D961-398D-4C5C-8DAA-919F17139695/Post/p1>
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: SELECT Z_MAX FROM Z_PRIMARYKEY WHERE Z_ENT = ?
CoreData: sql: UPDATE OR FAIL Z_PRIMARYKEY SET Z_MAX = ? WHERE Z_ENT = ? AND Z_MAX = ?
CoreData: sql: COMMIT
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: INSERT INTO ZSKILLMETADATA(Z_PK, Z_ENT, Z_OPT, ZSKILL, ZDIFFICULTY, ZISACTIVE, ZLATESTUPDATE, ZSECTIONIDENTIFIER, ZTHUMBNAIL) VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?)
CoreData: sql: COMMIT
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZISVIDEO, t0.ZMEDIAFILENAME, t0.ZNOTES, t0.ZPOSTIMAGE, t0.ZTIMESTAMP FROM ZPOST t0 WHERE t0.ZNOTES IS NOT NULL
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0002s for 0 rows.
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZISVIDEO, t0.ZMEDIAFILENAME, t0.ZNOTES, t0.ZPOSTIMAGE, t0.ZTIMESTAMP FROM ZPOST t0 WHERE ( t0.ZISVIDEO IS NOT NULL AND t0.ZISVIDEO = ?)
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0002s for 1 rows.
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: COMMIT
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: INSERT INTO ZRECORD(Z_PK, Z_ENT, Z_OPT, ZSKILL, ZRECORDTYPE, ZTIMESTAMP, ZIMAGEFILENAME) VALUES(?, ?, ?, ?, ?, ?, ?)
CoreData: sql: COMMIT
CoreData: sql: SELECT 0, t0.Z_PK, t0.Z_OPT, t0.ZISVIDEO, t0.ZMEDIAFILENAME, t0.ZNOTES, t0.ZPOSTIMAGE, t0.ZTIMESTAMP FROM ZPOST t0 WHERE ( t0.ZISVIDEO IS NOT NULL AND t0.ZISVIDEO = ?)
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0002s for 0 rows.
CoreData: sql: BEGIN EXCLUSIVE
CoreData: sql: UPDATE OR FAIL ZSKILLMETADATA SET Z_OPT = ? WHERE Z_PK = ? AND Z_OPT = ?
CoreData: sql: COMMIT
CoreData: sql: SELECT t0.Z_ENT, t0.Z_PK, Z_FOK_2TAGS FROM ZTAG t0 JOIN Z_1TAGS t1 ON t0.Z_PK = t1.Z_2TAGS WHERE t1.Z_1POSTS = ?
CoreData: annotation: sql connection fetch time: 0.0001s
CoreData: annotation: total fetch execution time: 0.0001s for 1 rows.
CoreData: annotation: to-many relationship fault "tags" for objectID 0x9de26d27ef2a7ac8 <x-coredata://DDA9D961-398D-4C5C-8DAA-919F17139695/Post/p1> fulfilled from database. Got 1 rows
2020-04-16 10:34:32.587088-0700 SweatNetOffline[33644:4324282] -[NSSymbolicExpression length]: unrecognized selector sent to instance 0x60000315f820
CoreData: annotation: Disconnecting from sqlite database.
CoreData: annotation: Disconnecting from sqlite database.
CoreData: annotation: Disconnecting from sqlite database.
2020-04-16 10:34:32.619490-0700 SweatNetOffline[33644:4324282] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSSymbolicExpression length]: unrecognized selector sent to instance 0x60000315f820'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff23c7127e __exceptionPreprocess + 350
1 libobjc.A.dylib 0x00007fff513fbb20 objc_exception_throw + 48
2 CoreFoundation 0x00007fff23c91fd4 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
3 CoreFoundation 0x00007fff23c75c4c ___forwarding___ + 1436
4 CoreFoundation 0x00007fff23c77f78 _CF_forwarding_prep_0 + 120
5 Foundation 0x00007fff257159b4 -[NSOrderedSet(NSKeyValueCoding) valueForKeyPath:] + 53
6 Foundation 0x00007fff257fea18 -[NSFunctionExpression expressionValueWithObject:context:] + 707
7 Foundation 0x00007fff257fe935 -[NSFunctionExpression expressionValueWithObject:context:] + 480
8 CoreData 0x00007fff238aa500 -[NSEntityMigrationPolicy createRelationshipsForDestinationInstance:entityMapping:manager:error:] + 1272
9 CoreData 0x00007fff238f5a98 -[NSMigrationManager(InternalMethods) _doSecondPassForMapping:error:] + 418
10 CoreData 0x00007fff238f6c00 -[NSMigrationManager(InternalMethods) _migrateStoreFromURL:type:options:withMappingModel:toDestinationURL:destinationType:destinationOptions:error:] + 2012
11 CoreData 0x00007fff238f3c9f -[NSMigrationManager migrateStoreFromURL:type:options:withMappingModel:toDestinationURL:destinationType:destinationOptions:error:] + 664
12 CoreData 0x00007fff239a5eab -[NSStoreMigrationPolicy(InternalMethods) migrateStoreAtURL:toURL:storeType:options:withManager:error:] + 254
13 CoreData 0x00007fff239a5466 -[NSStoreMigrationPolicy migrateStoreAtURL:withManager:metadata:options:error:] + 99
14 CoreData 0x00007fff239a6adf -[NSStoreMigrationPolicy(InternalMethods) _gatherDataAndPerformMigration:] + 2829
15 CoreData 0x00007fff238fc335 __91-[NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:]_block_invoke + 2469
16 CoreData 0x00007fff2390ceb9 gutsOfBlockToNSPersistentStoreCoordinatorPerform + 177
17 libdispatch.dylib 0x0000000110c5ed48 _dispatch_client_callout + 8
18 libdispatch.dylib 0x0000000110c6d9bf _dispatch_lane_barrier_sync_invoke_and_complete + 132
19 CoreData 0x00007fff238f88f9 _perform + 181
20 CoreData 0x00007fff237e9334 -[NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:] + 416
21 CoreData 0x00007fff238fb31b -[NSPersistentStoreCoordinator _doAddPersistentStoreWithDescription:privateCopy:completeOnMainThread:withHandler:] + 515
22 CoreData 0x00007fff238fb8ab -[NSPersistentStoreCoordinator addPersistentStoreWithDescription:completionHandler:] + 205
23 CoreData 0x00007fff238aef63 -[NSPersistentContainer _loadStoreDescriptons:withCompletionHandler:] + 272
24 CoreData 0x00007fff238aee2c -[NSPersistentContainer loadPersistentStoresWithCompletionHandler:] + 398
25 SweatNetOffline 0x000000010fa9dc05 $s15SweatNetOffline11AppDelegateC19persistentContainerSo012NSPersistentG0CvgAFyXEfU_ + 181
26 SweatNetOffline 0x000000010fa9da97 $s15SweatNetOffline11AppDelegateC19persistentContainerSo012NSPersistentG0Cvg + 375
27 SweatNetOffline 0x000000010fae8788 $s15SweatNetOffline19Home2ViewControllerC019skillFetchedResultsF033_A1FE4BA766270B7DD28F222CBF923E7DLLSo09NSFetchediF0CyAA13SkillMetaDataCGvgAJyXEfU_ + 360
28 SweatNetOffline 0x000000010fae5497 $s15SweatNetOffline19Home2ViewControllerC019skillFetchedResultsF033_A1FE4BA766270B7DD28F222CBF923E7DLLSo09NSFetchediF0CyAA13SkillMetaDataCGvg + 375
29 SweatNetOffline 0x000000010fae5771 $s15SweatNetOffline19Home2ViewControllerC11viewDidLoadyyF + 177
30 SweatNetOffline 0x000000010fae5c1b $s15SweatNetOffline19Home2ViewControllerC11viewDidLoadyyFTo + 43
31 UIKitCore 0x00007fff47a0ef01 -[UIViewController _sendViewDidLoadWithAppearanceProxyObjectTaggingEnabled] + 83
32 UIKitCore 0x00007fff47a13e5a -[UIViewController loadViewIfRequired] + 1084
33 UIKitCore 0x00007fff479781e4 -[UINavigationController _updateScrollViewFromViewController:toViewController:] + 160
34 UIKitCore 0x00007fff479784e8 -[UINavigationController _startTransition:fromViewController:toViewController:] + 144
35 UIKitCore 0x00007fff479793b6 -[UINavigationController _startDeferredTransitionIfNeeded:] + 868
36 UIKitCore 0x00007fff4797a721 -[UINavigationController __viewWillLayoutSubviews] + 150
37 UIKitCore 0x00007fff4795b553 -[UILayoutContainerView layoutSubviews] + 217
38 UIKitCore 0x00007fff485784bd -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2478
39 QuartzCore 0x00007fff2b131db1 -[CALayer layoutSublayers] + 255
40 QuartzCore 0x00007fff2b137fa3 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 517
41 QuartzCore 0x00007fff2b1438da _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 80
42 QuartzCore 0x00007fff2b08a848 _ZN2CA7Context18commit_transactionEPNS_11TransactionEd + 324
43 QuartzCore 0x00007fff2b0bfb51 _ZN2CA11Transaction6commitEv + 643
44 UIKitCore 0x00007fff480aa575 __34-[UIApplication _firstCommitBlock]_block_invoke_2 + 81
45 CoreFoundation 0x00007fff23bd429c __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
46 CoreFoundation 0x00007fff23bd3a08 __CFRunLoopDoBlocks + 312
47 CoreFoundation 0x00007fff23bce894 __CFRunLoopRun + 1284
48 CoreFoundation 0x00007fff23bce066 CFRunLoopRunSpecific + 438
49 GraphicsServices 0x00007fff384c0bb0 GSEventRunModal + 65
50 UIKitCore 0x00007fff48092d4d UIApplicationMain + 1621
51 SweatNetOffline 0x000000010fa9ea7b main + 75
52 libdyld.dylib 0x00007fff5227ec25 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
- Did the migration work? Any way to know if it worked and if this is an issue with my fetch request or if somehow the data was corrupted or if it never worked at all. What is the best way to check this?
抛出异常时，我认为迁移仍在进行中。如果您查看调用堆栈，堆栈中似乎更早发生了与迁移相关的调用：
1 ... objc_exception_throw + 48
2 ... [NSObject(NSObject) doesNotRecognizeSelector:] + 132
3 ... ___forwarding___ + 1436
4 ... _CF_forwarding_prep_0 + 120
5 ... [NSOrderedSet(NSKeyValueCoding) valueForKeyPath:] + 53
6 ... [NSFunctionExpression expressionValueWithObject:context:] + 707
7 ... [NSFunctionExpression expressionValueWithObject:context:] + 480
8 ... [NSEntityMigrationPolicy createRelationshipsForDestinationInstance:entityMapping:manager:error:] + 1272
9 ... [NSMigrationManager(InternalMethods) _doSecondPassForMapping:error:] + 418
10 ... [NSMigrationManager(InternalMethods) _migrateStoreFromURL:type:options:withMappingModel:toDestinationURL:destinationType:destinationOptions:error:] + 2012
我不会假设迁移已完成，只是因为调用了您的 viewDidLoad 方法：迁移可能异步发生 - 这取决于您的 CoreData 堆栈的创建方式。
- Why are there so many question marks in the SQL - does the mean that the migration is not working properly?
这正是您使用 SQLDebug 时 CoreData 记录值的方式。他们没什么好担心的。
- What is Z? all of the attributes seem to start with Z - "WHERE t0.ZNOTES IS NOT NULL" for instance
当 CoreData 创建 SQLite 数据库时，从广义上讲，它会为每个实体创建一个 table，其中的列表示属性。 table 名称和列名称总是（至少根据我的经验）以 "Z" 为前缀。所以，再说一次，Zs 不用担心。
- What is an NSSymbolicExpression? Where would it occur in the core data migration. I understand that somehow its trying to find the length of this object, and the object doesn't have that instance method. Does that mean it is assuming the migration is completed when it hasn't been for instance?
我的猜测是您的迁移代码中存在指针不匹配问题：指向类似 NSString（确实响应 length）的指针实际上指向 NSSymbolicExpression 对象（它不响应该选择器）。如果 NSString 对象被释放（并释放），并且它占用的内存随后分配给 NSSymbolicExpression 对象，则可能会发生这种情况。
我该如何调试它？我会首先在您的迁移代码中放置一个断点，然后单步执行以尝试找到有问题的代码。您还可以尝试启用 Zombie 跟踪（当访问已释放对象使用的内存时会发出标记）。这超出了我在这里所能涵盖的范围：一些谷歌搜索应该会有所帮助。