Question

我的应用程序在后台线程中进行更新，然后保存上下文更改。在主要上下文中，有一个与NSFetchedResultsController一起使用的表视图。有一段时间更新工作正常，但然后抛出异常。为了检查这一点，我已将NSLog(@"%@", [self.controller fetchedObjects]);添加到-controllerDidChangeContent:。这是我得到的：

"<PRBattle: 0x6d30530> (entity: PRBattle; id: 0x6d319d0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p2> ; data: {\n    battleId = \"-1\";\n    finishedAt = \"2012-11-06 11:37:36 +0000\";\n    opponent = \"0x6d2f730 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p1>\";\n    opponentScore = nil;\n    score = nil;\n    status = 4;\n})",
"<PRBattle: 0x6d306f0> (entity: PRBattle; id: 0x6d319f0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p1> ; data: {\n    battleId = \"-1\";\n    finishedAt = \"2012-11-06 11:37:36 +0000\";\n    opponent = \"0x6d2ddb0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p3>\";\n    opponentScore = nil;\n    score = nil;\n    status = 4;\n})",
"<PRBattle: 0x6d30830> (entity: PRBattle; id: 0x6d31650 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p11> ; data: <fault>)",
"<PRBattle: 0x6d306b0> (entity: PRBattle; id: 0x6d319e0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p5> ; data: {\n    battleId = 325;\n    finishedAt = nil;\n    opponent = \"0x6d2f730 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p1>\";\n    opponentScore = 91;\n    score = 59;\n    status = 3;\n})",
"<PRBattle: 0x6d30730> (entity: PRBattle; id: 0x6d31a00 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p6> ; data: {\n    battleId = 323;\n    finishedAt = nil;\n    opponent = \"0x6d2ddb0 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p3>\";\n    opponentScore = 0;\n    score = 0;\n    status = 3;\n})",
"<PRBattle: 0x6d307b0> (entity: PRBattle; id: 0x6d31630 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p9> ; data: {\n    battleId = 370;\n    finishedAt = \"2012-11-06 14:24:14 +0000\";\n    opponent = \"0x79a8e90 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p2>\";\n    opponentScore = 180;\n    score = 180;\n    status = 4;\n})",
"<PRBattle: 0x6d307f0> (entity: PRBattle; id: 0x6d31640 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p10> ; data: {\n    battleId = 309;\n    finishedAt = \"2012-11-02 01:19:27 +0000\";\n    opponent = \"0x79a8e90 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p2>\";\n    opponentScore = 120;\n    score = 240;\n    status = 4;\n})",
"<PRBattle: 0x6d30770> (entity: PRBattle; id: 0x6d31620 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p7> ; data: {\n    battleId = 315;\n    finishedAt = \"2012-11-02 02:26:24 +0000\";\n    opponent = \"0x79a8e90 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PROpponent/p2>\";\n    opponentScore = 119;\n    score = 179;\n    status = 4;\n})"

）

此处的故障对象（0xe972610）会导致崩溃。我在更新期间记录了数据并且在保存之前。此对象仅在updatedObjects中。为什么这个方法会返回“坏”对象？（此外，在更新期间，此对象几乎每次更新都会受到影响。并且只有在一些传递变为“坏”之后才会发生。）

P.S。：我使用RestKit来管理CoreData。

UPDATE2：

问题出现在[self.controller fetchedObjects]枚举中。它是从- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller调用的，看起来这些对象甚至在这个方法调用期间都被修改了（我的意思是CoreData更新还没有完成到那一点）。有可能吗？

更新：

当我做了smth时，得到了例外。像这样：

for (PRBattle *battle in [self.controller fetchedObjects) {
    switch (battle.statusScalar) {
        case ...
        default:
            [battle willAccessValueForKey:nil];
            NSAssert1(NO, @"Unexpected battle status found: %@", battle);
    }
}

例外与-willAccessValueForKey:一致。战斗的标量状态是枚举，即绑定到整数值1..4。我在switch的情况下提到了所有可能的值（高于default:）。最后一个有break;。因此，只有当battle.statusScalar返回非枚举值时才能使用此值。

PRBattle中的状态标量实现：

- (PRBattleStatuses)statusScalar
{
    [self willAccessValueForKey:@"statusScalar"];
    PRBattleStatuses result = (PRBattleStatuses)[self.status integerValue];
    [self didAccessValueForKey:@"statusScalar"];
    return result;
}

battle.status有验证规则： - 最小值：1 - 最大值：4 - 默认值：无值

最后一件事 - 调试日志：

objc[4664]: EXCEPTIONS: throwing 0x7d33f80 (object 0xe67d2a0, a _NSCoreDataException)
objc[4664]: EXCEPTIONS: searching through frame [ip=0x97b401 sp=0xbfffd9b0] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: catch(id)
objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x97b401 sp=0xbfffd9b0] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: handling exception 0x7d33f60 at 0x97b79f
objc[4664]: EXCEPTIONS: rethrowing current exception
objc[4664]: EXCEPTIONS: searching through frame [ip=0x97b911 sp=0xbfffd9b0] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: searching through frame [ip=0x9ac8b7 sp=0xbfffdc20] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: searching through frame [ip=0x97ee80 sp=0xbfffdc40] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: searching through frame [ip=0x361d0 sp=0xbfffdc70] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: searching through frame [ip=0xa701d8 sp=0xbfffde10] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: catch(id)
objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x97b911 sp=0xbfffd9b0] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: finishing handler
objc[4664]: EXCEPTIONS: searching through frame [ip=0x97b963 sp=0xbfffd9b0] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: searching through frame [ip=0x9ac8b7 sp=0xbfffdc20] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: searching through frame [ip=0x97ee80 sp=0xbfffdc40] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: searching through frame [ip=0x361d0 sp=0xbfffdc70] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: searching through frame [ip=0xa701d8 sp=0xbfffde10] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: catch(id)
objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x97b963 sp=0xbfffd9b0] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x9ac8b7 sp=0xbfffdc20] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x97ee80 sp=0xbfffdc40] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x361d0 sp=0xbfffdc70] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: unwinding through frame [ip=0x3656f sp=0xbfffdc70] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: unwinding through frame [ip=0xa701d8 sp=0xbfffde10] for exception 0x7d33f60
objc[4664]: EXCEPTIONS: handling exception 0x7d33f60 at 0xa701f5
2012-11-07 13:37:55.463 TestApp[4664:fb03] CoreData: error: Serious application error.  An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:.  CoreData could not fulfill a fault for '0x6d31650 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p10>' with userInfo {
    NSAffectedObjectsErrorKey =     (
        "<PRBattle: 0x6d30830> (entity: PRBattle; id: 0x6d31650 <x-coredata://882BD521-90CD-4682-B19A-000A4976E471/PRBattle/p10> ; data: <fault>)"
    );
}

Answer 1

崩溃主要原因：“在后台线程中保存容易出错”（http://developer.apple.com/library/ios/#documentation/cocoa/conceptual/CoreData/Articles/cdConcurrency.html//apple_ref / DOC / UID / TP40003385-SW7）。当然，我以前读过这个。但RestKit问题变得更大了。它适用于“contextForCurrentThread”。因此，您应该获得后台线程的唯一上下文（根据相同的文档）。但是你不能从主线程保存它，除非你直接传递它，导致在主线程中这个方法返回另一个上下文。当我看到这个时，我认为RestKit为我修复了这个问题（在“正常”保存期间，而不是从主线程中），但没有。

第二件事是NSFetchedResultsController。当您从[self.controller fetchedObjects]致电-controllerDidChangeContent:时，您应该做好准备，这个数组可以及时更改。我拿了这个数组，并进行枚举，检索必要的数据。在枚举过程中它被改变了（我认为，这是NSMutableArray返回到NSArray的wity类型转换 - 所以这种行为变得可能了）。你永远不会在“默认”行为中看到这种情况（当你为每个渲染的单元格获得objectForIndexPath:的对象时 - 如Apple示例中所示），但在我的应用程序中，我有其他单元格，除了包含数据对象。所以我需要生成自己的存储，而不是直接使用控制器的获取结果。这样我建议完全避免使用NSFetchedResultsController。我用简单的NSManagedObjectDidSaveNotification观察者替换它并每次加载数据。

CoreData更新问题

1 个答案: