コアデータでsigabrtエラーが発生する

Question

私は最初の部分を持っている瞬間にコアデータについて学んでいますが、次のテーブルビューで教授を保存しようとすると、私はエラーメッセージが表示されます。このエラーは8行目で発生します。

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{ 
    return 1; 
} 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    return [(NSSet *)[department valueForKey:@"Professors"] count]; // uses the department's 
    // "Professors" relationship to get the number of professors in the department entity 
} 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *CellIdentifier = @"ProfessorCell"; 

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 
    if (cell == nil) { 
     cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier] autorelease]; 
    } 

    NSManagedObject *professor = [[self sortProfessors] objectAtIndex:indexPath.row]; 
    cell.textLabel.text = [NSString stringWithFormat:@"%@ %@", 
          [[professor valueForKey:@"FirstName"] description], 
          [[professor valueForKey:@"LastName"] description]]; 
    cell.detailTextLabel.text = [[professor valueForKey:@"EMail"] description]; 
    return cell; 
} 

これはアプリケーションを実行すると印刷されます。

2012-04-24 17:43:08.808 BlahBlah[2905:b603] Department Saved in the persistent data store 
2012-04-24 17:43:08.812 BlahBlah[2905:b603] -[NSManagedObject count]: unrecognized selector sent to instance 0x5a84a70 
2012-04-24 17:43:08.815 BlahBlah[2905:b603] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSManagedObject count]: unrecognized selector sent to instance 0x5a84a70' 
*** Call stack at first throw: 
(
    0 CoreFoundation      0x00fa35a9 __exceptionPreprocess + 185 
    1 libobjc.A.dylib      0x010f7313 objc_exception_throw + 44 
    2 CoreFoundation      0x00fa50bb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187 
    3 CoreFoundation      0x00f14966 ___forwarding___ + 966 
    4 CoreFoundation      0x00f14522 _CF_forwarding_prep_0 + 50 
    5 BlahBlah       0x00005423 -[ProfessorListViewController tableView:numberOfRowsInSection:] + 115 
    6 UIKit        0x001db2b7 -[UISectionRowData refreshWithSection:tableView:tableViewRowData:] + 1834 
    7 UIKit        0x001d8d88 -[UITableViewRowData numberOfRows] + 108 
    8 UIKit        0x0008c677 -[UITableView noteNumberOfRowsChanged] + 132 
    9 UIKit        0x00099708 -[UITableView reloadData] + 773 
    10 BlahBlah       0x00005212 -[ProfessorListViewController viewWillAppear:] + 146 
    11 UIKit        0x000d8210 -[UINavigationController viewWillAppear:] + 334 
    12 UIKit        0x002ce8e4 -[UIWindowController transition:fromViewController:toViewController:target:didEndSelector:] + 6192 
    13 UIKit        0x000d3385 -[UIViewController _dismissModalViewControllerWithTransition:from:] + 2058 
    14 UIKit        0x000cfeb8 -[UIViewController dismissModalViewControllerWithTransition:] + 940 
    15 BlahBlah       0x000060d8 -[ProfessorDataEntryController save:] + 648 
    16 UIKit        0x0001e4fd -[UIApplication sendAction:to:from:forEvent:] + 119 
    17 UIKit        0x000ae799 -[UIControl sendAction:to:forEvent:] + 67 
    18 UIKit        0x000b0c2b -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 527 
    19 UIKit        0x000af7d8 -[UIControl touchesEnded:withEvent:] + 458 
    20 UIKit        0x00042ded -[UIWindow _sendTouchesForEvent:] + 567 
    21 UIKit        0x00023c37 -[UIApplication sendEvent:] + 447 
    22 UIKit        0x00028f2e _UIApplicationHandleEvent + 7576 
    23 GraphicsServices     0x011dc992 PurpleEventCallback + 1550 
    24 CoreFoundation      0x00f84944 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52 
    25 CoreFoundation      0x00ee4cf7 __CFRunLoopDoSource1 + 215 
    26 CoreFoundation      0x00ee1f83 __CFRunLoopRun + 979 
    27 CoreFoundation      0x00ee1840 CFRunLoopRunSpecific + 208 
    28 CoreFoundation      0x00ee1761 CFRunLoopRunInMode + 97 
    29 GraphicsServices     0x011db1c4 GSEventRunModal + 217 
    30 GraphicsServices     0x011db289 GSEventRun + 115 
    31 UIKit        0x0002cc93 UIApplicationMain + 1160 
    32 BlahBlah       0x00001ba9 main + 121 
    33 BlahBlah       0x00001b25 start + 53 
) 
terminate called throwing an exceptionsharedlibrary apply-load-rules all 
Current language: auto; currently objective-c 
(gdb) 

Answer 1

あなたのモデルを見て、「教授」がDepartmentの多対多関係として宣言されていることを確認してください。