Question

I am trying to run the following code:

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"CellIdentifier";
    GradeToolAppDelegate * appDelegate = [UIApplication sharedApplication].delegate;
    appDelegate = [UIApplication sharedApplication].delegate;
    // Dequeue or create a cell of the appropriate type.
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
        cell.accessoryType = UITableViewCellAccessoryNone;
    }
    NSLog(@"Array Count: %d", [appDelegate.modules count]);
    // Configure the cell.
    //cell.textLabel.text = [NSString stringWithFormat:@"Row %d", indexPath.row];
    //Module * aModule = [appDelegate.modules objectAtIndex:indexPath.row];
    //cell.textLabel.text = aModule.moduleTitle;
    return cell;
}

But it just crashes the app with:

2011-05-20 15:38:09.256 GradeTool[3994:207] -[GradeToolAppDelegate modules]: unrecognized selector sent to instance 0x5523f80
2011-05-20 15:38:09.258 GradeTool[3994:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[GradeToolAppDelegate modules]: unrecognized selector sent to instance 0x5523f80'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x00eebbe9 __exceptionPreprocess + 185
    1   libobjc.A.dylib                     0x00ce05c2 objc_exception_throw + 47
    2   CoreFoundation                      0x00eed6fb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
    3   CoreFoundation                      0x00e5d366 ___forwarding___ + 966
    4   CoreFoundation                      0x00e5cf22 _CF_forwarding_prep_0 + 50
    5   GradeTool                           0x000037ff -[RootViewController tableView:cellForRowAtIndexPath:] + 322
    6   UIKit                               0x003367fa -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:withIndexPath:] + 634
    7   UIKit                               0x0032c77f -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:] + 75
    8   UIKit                               0x00341450 -[UITableView(_UITableViewPrivate) _updateVisibleCellsNow:] + 1561
    9   UIKit                               0x00339538 -[UITableView layoutSubviews] + 242
    10  QuartzCore                          0x01ff8451 -[CALayer layoutSublayers] + 181
    11  QuartzCore                          0x01ff817c CALayerLayoutIfNeeded + 220
    12  QuartzCore                          0x01ff137c _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 310
    13  QuartzCore                          0x01ff10d0 _ZN2CA11Transaction6commitEv + 292
    14  UIKit                               0x002c519f -[UIApplication _reportAppLaunchFinished] + 39
    15  UIKit                               0x002c5659 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 690
    16  UIKit                               0x002cfdb2 -[UIApplication handleEvent:withNewEvent:] + 1533
    17  UIKit                               0x002c8202 -[UIApplication sendEvent:] + 71
    18  UIKit                               0x002cd732 _UIApplicationHandleEvent + 7576
    19  GraphicsServices                    0x01a70a36 PurpleEventCallback + 1550
    20  CoreFoundation                      0x00ecd064 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
    21  CoreFoundation                      0x00e2d6f7 __CFRunLoopDoSource1 + 215
    22  CoreFoundation                      0x00e2a983 __CFRunLoopRun + 979
    23  CoreFoundation                      0x00e2a240 CFRunLoopRunSpecific + 208
    24  CoreFoundation                      0x00e2a161 CFRunLoopRunInMode + 97
    25  UIKit                               0x002c4fa8 -[UIApplication _run] + 636
    26  UIKit                               0x002d142e UIApplicationMain + 1160
    27  GradeTool                           0x00002960 main + 102
    28  GradeTool                           0x000028f1 start + 53
)
terminate called after throwing an instance of 'NSException'

The GradeToolAppDelegate * appDelegate = [UIApplication sharedApplication].delegate; seems to be one of the major problems, and when running NSLog(@"Array Count: %d", [appDelegate.modules count]); causes the exception

Can anyone help me out here on what I am doing wrong.

Thanks.

Answer 1

Your GradeToolAppDelegate does not have a modules method defined. Seeing that you are referencing via dot-notation, I’d assume you forgot to either: define the property and/or synthesize the property.