我收到此错误：
2013-01-21 15:09:49.479 obtl[13136:403] An uncaught exception was raised
2013-01-21 15:09:49.484 obtl[13136:403] [<NSApplication 0x10012a600> valueForUndefinedKey:]: this class is not key value coding-compliant for the key managedObjectContext.
2013-01-21 15:09:49.493 obtl[13136:403] (
0 CoreFoundation 0x00007fff8c000f56 __exceptionPreprocess + 198
1 libobjc.A.dylib 0x00007fff934f4d5e objc_exception_throw + 43
2 CoreFoundation 0x00007fff8c08b1b9 -[NSException raise] + 9
3 Foundation 0x00007fff8ef65703 -[NSObject(NSKeyValueCoding) valueForUndefinedKey:] + 240
4 Foundation 0x00007fff8ee9c38e _NSGetUsingKeyValueGetter + 108
5 Foundation 0x00007fff8ee9c315 -[NSObject(NSKeyValueCoding) valueForKey:] + 392
6 AppKit 0x00007fff938596ef -[NSApplication(NSScripting) valueForKey:] + 510
7 Foundation 0x00007fff8eebbda2 -[NSObject(NSKeyValueCoding) valueForKeyPath:] + 348
8 AppKit 0x00007fff936572fa -[NSBinder _valueForKeyPath:ofObject:mode:raisesForNotApplicableKeys:] + 654
9 AppKit 0x00007fff93656fe4 -[NSBinder valueForBinding:resolveMarkersToPlaceholders:] + 171
10 AppKit 0x00007fff93656c52 -[NSObjectParameterBinder _updateObject:observedController:observedKeyPath:context:] + 1181
11 AppKit 0x00007fff93648f8f -[NSObject(NSKeyValueBindingCreation) bind:toObject:withKeyPath:options:] + 591
12 AppKit 0x00007fff936422a1 -[NSIBObjectData nibInstantiateWithOwner:topLevelObjects:] + 1079
13 AppKit 0x00007fff936388bb loadNib + 322
14 AppKit 0x00007fff93637db8 +[NSBundle(NSNibLoading) _loadNibFile:nameTable:withZone:ownerBundle:] + 217
15 AppKit 0x00007fff93637cd3 +[NSBundle(NSNibLoading) loadNibFile:externalNameTable:withZone:] + 141
16 AppKit 0x00007fff93637c16 +[NSBundle(NSNibLoading) loadNibNamed:owner:] + 364
17 AppKit 0x00007fff938a8cd7 NSApplicationMain + 398
18 obtl 0x0000000100001b52 main + 34
19 obtl 0x0000000100001b24 start + 52
)
2013-01-21 15:09:49.503 obtl[13136:403] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<NSApplication 0x10012a600> valueForUndefinedKey:]: this class is not key value coding-compliant for the key managedObjectContext.'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff8c000f56 __exceptionPreprocess + 198
1 libobjc.A.dylib 0x00007fff934f4d5e objc_exception_throw + 43
2 CoreFoundation 0x00007fff8c08b1b9 -[NSException raise] + 9
3 Foundation 0x00007fff8ef65703 -[NSObject(NSKeyValueCoding) valueForUndefinedKey:] + 240
4 Foundation 0x00007fff8ee9c38e _NSGetUsingKeyValueGetter + 108
5 Foundation 0x00007fff8ee9c315 -[NSObject(NSKeyValueCoding) valueForKey:] + 392
6 AppKit 0x00007fff938596ef -[NSApplication(NSScripting) valueForKey:] + 510
7 Foundation 0x00007fff8eebbda2 -[NSObject(NSKeyValueCoding) valueForKeyPath:] + 348
8 AppKit 0x00007fff936572fa -[NSBinder _valueForKeyPath:ofObject:mode:raisesForNotApplicableKeys:] + 654
9 AppKit 0x00007fff93656fe4 -[NSBinder valueForBinding:resolveMarkersToPlaceholders:] + 171
10 AppKit 0x00007fff93656c52 -[NSObjectParameterBinder _updateObject:observedController:observedKeyPath:context:] + 1181
11 AppKit 0x00007fff93648f8f -[NSObject(NSKeyValueBindingCreation) bind:toObject:withKeyPath:options:] + 591
12 AppKit 0x00007fff936422a1 -[NSIBObjectData nibInstantiateWithOwner:topLevelObjects:] + 1079
13 AppKit 0x00007fff936388bb loadNib + 322
14 AppKit 0x00007fff93637db8 +[NSBundle(NSNibLoading) _loadNibFile:nameTable:withZone:ownerBundle:] + 217
15 AppKit 0x00007fff93637cd3 +[NSBundle(NSNibLoading) loadNibFile:externalNameTable:withZone:] + 141
16 AppKit 0x00007fff93637c16 +[NSBundle(NSNibLoading) loadNibNamed:owner:] + 364
17 AppKit 0x00007fff938a8cd7 NSApplicationMain + 398
18 obtl 0x0000000100001b52 main + 34
19 obtl 0x0000000100001b24 start + 52
)
terminate called throwing an exception
相关信息：
Mac OSX App（试图让拥有 Snow Leopard 的用户也能使用它）。一切都适当地绑定到FileOwner.managedObjectContext适当的实体。我已经三次检查了我所有的表格、按钮等，以确保它们连接到正确的绑定。我只有 1 个窗口文件。我在 Mac Lion 上使用 Xcode 4.5.2（不使用自动布局）。我不知道如何解决这个问题——是的，我研究了很多类似的问题，并尝试了一些相同的解决方案，但无济于事。