ios - [setValue:forUndefinedKey:]

Question

ビルドが成功して終了する別の問題。次のように：

エラー：

2013-09-30 20:21:23.708 The Solver[2566:a0b] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<UIView 0x89bfd40> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key welcomeBeta.'
*** First throw call stack:
(
    0   CoreFoundation                      0x023615e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x014bf8b6 objc_exception_throw + 44
    2   CoreFoundation                      0x023f16a1 -[NSException raise] + 17
    3   Foundation                          0x00f73c2e -[NSObject(NSKeyValueCoding) setValue:forUndefinedKey:] + 282
    4   Foundation                          0x00edff3b _NSSetUsingKeyValueSetter + 88
    5   Foundation                          0x00edf493 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 267
    6   UIKit                               0x0008f97b -[UIView(CALayerDelegate) setValue:forKey:] + 168
    7   Foundation                          0x00f4194a -[NSObject(NSKeyValueCoding) setValue:forKeyPath:] + 412
    8   UIKit                               0x002c6cd5 -[UIRuntimeOutletConnection connect] + 106
    9   libobjc.A.dylib                     0x014d17d2 -[NSObject performSelector:] + 62
    10  CoreFoundation                      0x0235cb6a -[NSArray makeObjectsPerformSelector:] + 314
    11  UIKit                               0x002c582e -[UINib instantiateWithOwner:options:] + 1417
    12  UIKit                               0x00137c95 -[UIViewController _loadViewFromNibNamed:bundle:] + 280
    13  UIKit                               0x0013843d -[UIViewController loadView] + 302
    14  UIKit                               0x0013873e -[UIViewController loadViewIfRequired] + 78
    15  UIKit                               0x00138c44 -[UIViewController view] + 35
    16  UIKit                               0x000615ad -[UIWindow addRootViewControllerViewIfPossible] + 66
    17  UIKit                               0x00061947 -[UIWindow _setHidden:forced:] + 312
    18  UIKit                               0x00061bdd -[UIWindow _orderFrontWithoutMakingKey] + 49
    19  UIKit                               0x0006c44a -[UIWindow makeKeyAndVisible] + 65
    20  UIKit                               0x0001f8e0 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1851
    21  UIKit                               0x00023fb8 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 824
    22  UIKit                               0x0003842c -[UIApplication handleEvent:withNewEvent:] + 3447
    23  UIKit                               0x00038999 -[UIApplication sendEvent:] + 85
    24  UIKit                               0x00025c35 _UIApplicationHandleEvent + 736
    25  GraphicsServices                    0x022bf2eb _PurpleEventCallback + 776
    26  GraphicsServices                    0x022bedf6 PurpleEventCallback + 46
    27  CoreFoundation                      0x022dcdd5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53
    28  CoreFoundation                      0x022dcb0b __CFRunLoopDoSource1 + 523
    29  CoreFoundation                      0x023077ec __CFRunLoopRun + 2156
    30  CoreFoundation                      0x02306b33 CFRunLoopRunSpecific + 467
    31  CoreFoundation                      0x0230694b CFRunLoopRunInMode + 123
    32  UIKit                               0x000236ed -[UIApplication _run] + 840
    33  UIKit                               0x0002594b UIApplicationMain + 1225
    34  The Solver                          0x000033dd main + 141
    35  libdyld.dylib                       0x059a5725 start + 0
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

welcomeBeta (ボタン) を使用した UIControllerView のコード

WelcomeUI.h:

#import <UIKit/UIKit.h>

@interface WelcomeUI : UIViewController

@property (weak, nonatomic) IBOutlet UIButton *welcomeStart;

@property (weak, nonatomic) IBOutlet UIButton *welcomeBeta;

@end

WelcomeUI.m:

#import "WelcomeUI.h"

@interface WelcomeUI ()

@end

@implementation WelcomeUI

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

どこが間違っているのか教えてください。また、objective-c と Xcode は初めてなので、詳しく説明してください。