我最近尝试创建一个名为signupComplete的隐藏按钮，突然之间我每次尝试运行应用程序时都会收到此错误。这是我在控制台中收到的错误消息：
*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<SignupViewController 0x10a3519f0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key signupComplete.'
我不知道为什么我会这样做。我甚至回去删除了与signupComplete按钮有关的任何内容，但我仍然收到此错误。
*** First throw call stack: (
0 CoreFoundation 0x0000000102846495 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x00000001025a599e objc_exception_throw + 43
2 CoreFoundation 0x00000001028ca919 -[NSException raise] + 9
3 Foundation 0x0000000102186530 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 259
4 CoreFoundation 0x0000000102842400 -[NSArray makeObjectsPerformSelector:] + 224
5 UIKit 0x00000001013ad8a6 -[UINib instantiateWithOwner:options:] + 1131
6 UIKit 0x0000000101247b0c -[UIViewController _loadViewFromNibNamed:bundle:] + 245
7 UIKit 0x0000000101248149 -[UIViewController loadView] + 112
8 UIKit 0x00000001012483b7 -[UIViewController loadViewIfRequired] + 75
9 UIKit 0x0000000101248777 -[UIViewController view] + 29
10 UIKit 0x000000010125f2c5 -[UINavigationController _startCustomTransition:] + 628
11 UIKit 0x000000010126a6f5 -[UINavigationController _startDeferredTransitionIfNeeded:] + 401
12 UIKit 0x000000010126b238 -[UINavigationController __viewWillLayoutSubviews] + 43
13 UIKit 0x0000000101385895 -[UILayoutContainerView layoutSubviews] + 202
14 UIKit 0x00000001011b2993 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 354
15 QuartzCore 0x00000001004d5802 -[CALayer layoutSublayers] + 151
16 QuartzCore 0x00000001004ca369 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 363
17 QuartzCore 0x00000001004ca1ea _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24
18 QuartzCore 0x000000010043dfb8 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 252
19 QuartzCore 0x000000010043f030 _ZN2CA11Transaction6commitEv + 394
20 UIKit 0x0000000101151024 _UIApplicationHandleEventQueue + 10914
21 CoreFoundation 0x00000001027d5d21 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
22 CoreFoundation 0x00000001027d55f2 __CFRunLoopDoSources0 + 242
23 CoreFoundation 0x00000001027f146f __CFRunLoopRun + 767
24 CoreFoundation 0x00000001027f0d83 CFRunLoopRunSpecific + 467
25 GraphicsServices 0x000000010459ef04 GSEventRunModal + 161
26 UIKit 0x0000000101152e33 UIApplicationMain + 1010
27 PickPiic 0x0000000100002853 main + 115
28 libdyld.dylib 0x00000001031855fd start + 1
29 ??? 0x0000000000000001 0x0 + 1
） libc ++ abi.dylib：以NSException类型的未捕获异常终止 （lldb）