我正在使用一个教程来编写一个相当简单的应用程序。我今天将应用程序复制到我的工作电脑上。昨晚在我的笔记本电脑上它完美地运作，但今天我得到了这个错误。我试图削减几乎所有的代码，甚至删除了didFinishLaunchingWithOptions函数中的所有内容，但我仍然得到这个错误。我甚至没有在任何地方声明过 navBar！我认为问题在于代码之外的某种项目或文件设置？
2011-11-22 14:39:32.294 LetsEat[15320:b603] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<LetsEatAppDelegate 0x5a824a0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key navBar.'
*** Call stack at first throw:
(
0 CoreFoundation 0x00fa45a9 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x010f8313 objc_exception_throw + 44
2 CoreFoundation 0x00fa44e1 -[NSException raise] + 17
3 Foundation 0x0079f677 _NSSetUsingKeyValueSetter + 135
4 Foundation 0x0079f5e5 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 285
5 UIKit 0x0021b30c -[UIRuntimeOutletConnection connect] + 112
6 CoreFoundation 0x00f1a8cf -[NSArray makeObjectsPerformSelector:] + 239
7 UIKit 0x00219d23 -[UINib instantiateWithOwner:options:] + 1041
8 UIKit 0x0021bab7 -[NSBundle(UINSBundleAdditions) loadNibNamed:owner:options:] + 168
9 UIKit 0x0002117a -[UIApplication _loadMainNibFile] + 172
10 UIKit 0x00021cf4 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 291
11 UIKit 0x0002c617 -[UIApplication handleEvent:withNewEvent:] + 1533
12 UIKit 0x00024abf -[UIApplication sendEvent:] + 71
13 UIKit 0x00029f2e _UIApplicationHandleEvent + 7576
14 GraphicsServices 0x011dd992 PurpleEventCallback + 1550
15 CoreFoundation 0x00f85944 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
16 CoreFoundation 0x00ee5cf7 __CFRunLoopDoSource1 + 215
17 CoreFoundation 0x00ee2f83 __CFRunLoopRun + 979
18 CoreFoundation 0x00ee2840 CFRunLoopRunSpecific + 208
19 CoreFoundation 0x00ee2761 CFRunLoopRunInMode + 97
20 UIKit 0x000217d2 -[UIApplication _run] + 623
21 UIKit 0x0002dc93 UIApplicationMain + 1160
22 LetsEat 0x00001c99 main + 121
23 LetsEat 0x00001c15 start + 53
)
terminate called throwing an exceptionCurrent language: auto; currently objective-c
(gdb)
编辑：这是我的delegate.m文件顶部。正如你所看到的，它完全是模板代码：
#import "LetsEatAppDelegate.h"
//#import "ItemsViewController.h"
@implementation LetsEatAppDelegate
@synthesize window = _window;
@synthesize managedObjectContext = __managedObjectContext;
@synthesize managedObjectModel = __managedObjectModel;
@synthesize persistentStoreCoordinator = __persistentStoreCoordinator;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
[self.window makeKeyAndVisible];
return YES;
}
我已经删除了项目中的其他文件，但仍然收到此错误。
编辑2
目前为止，在我的工作电脑上才会出现此错误。相同版本的XCode（4.2.1），完全相同的文件在我的家用笔记本电脑上运行得很好。