释放的时候kvo crash了。。。。iOS8.1模拟器

[jl322137]

2015-10-09 18:14:45.803 Qingwen[74545:2004789] *** Terminating app due to uncaught exception 'NSRangeException', reason: 'Cannot remove an observer <UIStackView 0x7fb183c8d350> for the key path "hidden" from <UIStackView 0x7fb183c99490> because it is not registered as an observer.'
*** First throw call stack:
(
0 CoreFoundation 0x00000001074b7f35 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x0000000107124bb7 objc_exception_throw + 45
2 CoreFoundation 0x00000001074b7e6d +[NSException raise:format:] + 205
3 Foundation 0x0000000104375609 -[NSObject(NSKeyValueObserverRegistration) _removeObserver:forProperty:] + 608
4 Foundation 0x000000010437530c -[NSObject(NSKeyValueObserverRegistration) removeObserver:forKeyPath:] + 90
5 Qingwen 0x0000000102ec018b -[FDStackView removeHiddenObserverForView:] + 91
6 Qingwen 0x0000000102ebf8e5 -[FDStackView removeArrangedSubview:] + 421
7 Qingwen 0x0000000102ebf6fe -[FDStackView willRemoveSubview:] + 62
8 UIKit 0x000000010526649c __UIViewWillBeRemovedFromSuperview + 142
9 UIKit 0x00000001052661c9 -[UIView(Hierarchy) removeFromSuperview] + 91
10 UIKit 0x0000000105259e39 -[UIView dealloc] + 404
11 Qingwen 0x0000000102ec04af -[FDStackView dealloc] + 223
12 CoreFoundation 0x000000010738f78b CFRelease + 603
13 CoreFoundation 0x00000001073a30bd -[__NSArrayM dealloc] + 157
14 libobjc.A.dylib 0x000000010713928e _ZN11objc_object17sidetable_releaseEb + 236
15 libobjc.A.dylib 0x00000001071398cd _ZN12_GLOBAL__N_119AutoreleasePoolPage3popEPv + 591
16 CoreFoundation 0x00000001073aeda6 _CFAutoreleasePoolPop + 22
17 CoreFoundation 0x00000001073e2ef3 __CFRunLoopRun + 2051
18 CoreFoundation 0x00000001073e2486 CFRunLoopRunSpecific + 470
19 GraphicsServices 0x000000010a31c9f0 GSEventRunModal + 161
20 UIKit 0x00000001051fb420 UIApplicationMain + 1282
21 Qingwen 0x0000000102ea4e0f main + 111
22 libdyld.dylib 0x00000001081ce145 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

[sunnyxx]

已经修复，谢谢