Problem with objective-c troubleShooting

Question

Level 1

8 points

Problem with objective-c troubleShooting

Hi there,
i'm all new to mac & iOS developement and am getting startet by working throught what appeared to be a great book "Einstieg in Objective-C 2.0 and Cocoa inkl iPhone programming".

what im doing right now is creating an Weblog App for the iPhone by following stepBy step coding and interface instructions by this book.

problem: everything seems to work just fine, i can compile and everything. but one funktion does not work which is creating a new article.

the errorcode looks like that:

+2011-01-25 14:59:28.775 WeblogClientTouch[12682:207] Fehler beim Anlegen eines neuen Artikels+

and is produced by an NSLog:

if (![managedObjectContext save:&error]) {
NSLog(@"Fehler beim Anlegen eines neuen Artikels");
}

so apparently the saving of a new entity 'article' does not work. here some code snippets that might help, first the function that creates a new article in which the error occurs:


- (IBAction)neuerArtikel
{
 //erzeuge artikel
 NSEntityDescription *artikelDescription = [[fetchedResultsController fetchRequest]entity];
 NSManagedObject *newArtikel = [NSEntityDescription insertNewObjectForEntityForName:[artikelDescription name] 
 inManagedObjectContext:managedObjectContext];
 
 //befülle artikel mit standardwerten
 [newArtikel setValue:NSLocalizedString(@"Neuer Artikel", nil) 
 forKey:@"titel"];
 [newArtikel setValue:[NSDate date] forKey:@"datum"];
 [newArtikel setValue:@"Markus" forKey:@"autor"];
 
 //speichere artikel
 NSError *error;
 
 if (![managedObjectContext save:&error]) {
 NSLog(@"Fehler beim Anlegen eines neuen Artikels");
 }
 
 //Tableview aktualisieren
 [self.tableView reloadData];
}

in my datamodel i have only one entity named "Artikel" with the attributes: autor, titel, datum, inhalt.

i would be very glad about some tips, because i've been trying to solve the problem for nearly 3 hours now and i dont think it can be that tricky..

Message was edited by: sfluecki

Message was edited by: sfluecki

macbook pro, Mac OS X (10.6.6)

Posted on Jan 25, 2011 6:17 AM

Reply

Answer 1

sfluecki Author

Level 1

8 points

Jan 25, 2011 7:45 AM in response to sfluecki

so i've come a bit further while learning how to use the debugger in Xcode:

<NSManagedObject: 0x60336e0> (entity: Artikel; id: 0x6033750 <x-coredata:///Artikel/tD07EDF16-C361-4D3E-9564-5A0D9426BC052> ; data: {
 autor = Markus;
 datum = "2011-01-25 15:41:13 +0000";
 inhalt = nil;
 titel = "Neuer Artikel";

so: my object has been initialised properly, the problem must lie in the task
of saving itself in his container managedObjectContext.

please someone help me.. its now been over 5h of nonstop searching this
one error that keeps me from advancing which is quite frustrating :/

i've programmed before in c++, java and know about the troubles you can
have while programming - but i've never been that frustratedand near to
resigning 🙂

Reply

Answer 2

xnav

Level 5

7,089 points

Jan 25, 2011 7:46 AM in response to sfluecki

It may help to get the error info:


NSLog(@"ErrorInfo %@, %@", error, [error userInfo]);

Reply

Answer 3

sfluecki Author

Level 1

8 points

Jan 25, 2011 7:50 AM in response to sfluecki

thx for taking over here, i just changed the NSLog, what came out in gdb is this:


Pending breakpoint 1 - ""ArtikelOverviewController.m":65" resolved
(gdb) step
Current language: auto; currently objective-c
(gdb) step
2011-01-25 16:49:15.031 WeblogClientTouch[15978:207] ErrorInfo Error Domain=NSCocoaErrorDomain Code=1570 "The operation couldn’t be completed. (Cocoa error 1570.)" UserInfo=0x4d5e9e0 {NSValidationErrorObject=<NSManagedObject: 0x60211f0> (entity: Artikel; id: 0x6021260 <x-coredata:///Artikel/tC371BE7F-B7E2-47D8-A75C-21EC1249994D2> ; data: {
 autor = Markus;
 datum = "2011-01-25 15:49:11 +0000";
 inhalt = nil;
 titel = "Neuer Artikel";
}), NSValidationErrorKey=inhalt, NSLocalizedDescription=The operation couldn’t be completed. (Cocoa error 1570.)}, {
 NSLocalizedDescription = "The operation couldnU2019t be completed. (Cocoa error 1570.)";
 NSValidationErrorKey = inhalt;
 NSValidationErrorObject = "<NSManagedObject: 0x60211f0> (entity: Artikel; id: 0x6021260 <x-coredata:///Artikel/tC371BE7F-B7E2-47D8-A75C-21EC1249994D2> ; data: { autor = Markus; datum = "2011-01-25 15:49:11 +0000"; inhalt = nil; titel = "Neuer Artikel"; })";
}

seems to be an error with xDataModel, am i right?

Reply

Answer 4

xnav

Level 5

7,089 points

Jan 25, 2011 7:57 AM in response to sfluecki

seems to be an error with xDataModel, am i right?

Probably, are you seeing any error messages in Applications>Utilities>Console?

Reply

Answer 5

sfluecki Author

Level 1

8 points

Jan 25, 2011 8:02 AM in response to sfluecki

yes - i posted the errorcode you demanded in the last post.

anyways - i worked out a way aroud it by giving the attribute inhalt some random
value - the 'nil' seemed to be the problem there.

funny fact: i can now add without error, but the new article wont show in the window
until i restart the application ..

Reply

Answer 6

xnav

Level 5

7,089 points

Jan 25, 2011 8:08 AM in response to sfluecki

Your data model must have specified a value is required.

Reply

Answer 7

sfluecki Author

Level 1

8 points

Jan 25, 2011 8:13 AM in response to sfluecki

yes.
but if i activate 'optional' with the attributes i get the following SIGBART:


[Session started at 2011-01-25 17:12:22 +0100.]
2011-01-25 17:12:23.019 WeblogClientTouch[16340:207] Unresolved error Error Domain=NSCocoaErrorDomain Code=134100 "The operation couldn’t be completed. (Cocoa error 134100.)" UserInfo=0x60420f0 {metadata=<CFBasicHash 0x6041510 [0xff63e0]>{type = immutable dict, count = 7,
entries =>
 2 : <CFString 0x60418f0 [0xff63e0]>{contents = "NSStoreModelVersionIdentifiers"} = <CFArray 0x6041cc0 [0xff63e0]>{type = immutable, count = 0, values = ()}
 4 : <CFString 0x6041bf0 [0xff63e0]>{contents = "NSPersistenceFrameworkVersion"} = <CFNumber 0x60417c0 [0xff63e0]>{value = +320, type = kCFNumberSInt64Type}
 6 : <CFString 0x6041c20 [0xff63e0]>{contents = "NSStoreModelVersionHashes"} = <CFBasicHash 0x6041d50 [0xff63e0]>{type = immutable dict, count = 1,
entries =>
 1 : <CFString 0x6041ce0 [0xff63e0]>{contents = "Artikel"} = <CFData 0x6041d00 [0xff63e0]>{length = 32, capacity = 32, bytes = 0x6e935616c5185463f5370ab26eb5f6cf ... 3b2640026f034ca7}
}
 7 : <CFString 0xdfd4e4 [0xff63e0]>{contents = "NSStoreUUID"} = <CFString 0x6041a60 [0xff63e0]>{contents = "2C36DD32-3AB0-45A9-A9FF-A8606B64C8EB"}
 8 : <CFString 0xdfd354 [0xff63e0]>{contents = "NSStoreType"} = <CFString 0xdfd524 [0xff63e0]>{contents = "SQLite"}
 9 : <CFString 0x6041c70 [0xff63e0]>{contents = "NSStoreModelVersionHashesVersion"} = <CFNumber 0x4d22210 [0xff63e0]>{value = +3, type = kCFNumberSInt32Type}
 10 : <CFString 0x6041ca0 [0xff63e0]>{contents = "_NSAutoVacuumLevel"} = <CFString 0x6041da0 [0xff63e0]>{contents = "2"}
}
, reason=The model used to open the store is incompatible with the one used to create the store}, {
 metadata = {
 NSPersistenceFrameworkVersion = 320;
 NSStoreModelVersionHashes = {
 Artikel = <6e935616 c5185463 f5370ab2 6eb5f6cf 0f97e563 2f305347 3b264002 6f034ca7>;
 };
 NSStoreModelVersionHashesVersion = 3;
 NSStoreModelVersionIdentifiers = (
 );
 NSStoreType = SQLite;
 NSStoreUUID = "2C36DD32-3AB0-45A9-A9FF-A8606B64C8EB";
 "_NSAutoVacuumLevel" = 2;
 };
 reason = "The model used to open the store is incompatible with the one used to create the store";
}

Reply

Answer 8

sfluecki Author

Level 1

8 points

Jan 25, 2011 8:18 AM in response to sfluecki

to make it easier i've made .zip of the whole project (740kb or something)
its on my own server - its secure.

http://www.sflueckiger.ch/html/data/WeblogClientTouch.zip

Reply

Answer 9

xnav

Level 5

7,089 points

Jan 25, 2011 10:12 AM in response to sfluecki

If you change the model you either have to delete the existing permanent store or see +Lightweight Migration+ in the +Core Data Model Versioning and Data Migration Programming Guide+.

Reply

Answer 10

sfluecki Author

Level 1

8 points

Jan 25, 2011 10:54 AM in response to sfluecki

allRight.
i got it working so far that there's no more errors.

--> i can now klick on 'new article' without any errors, but my tableView does not show the new allocated articles
--> after i restart the app (rebuild, reRun in simulator) the previously added articles are showing in the tableView.

--> somehow my tableView does just update itself whilst starting the app.

in the end of the 'addNewArticle' function i have the following:

[self.tableView reloadData];

the tableView itself is defined by the following:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
 NSArray *sections = [fetchedResultsController sections];
 NSUInteger count = 0;
 if ([sections count]) {
 id <NSFetchedResultsSectionInfo> sectionInfo = [sections objectAtIndex:section];
 count = [sectionInfo numberOfObjects];
 }
 return count;
}

and

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
 static NSString *CellIdentifier = @"Cell";
 
 //Zelle aus dem Cache holen oder erzeugen wenn nicht orhanden
 UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
 if (cell == nil) {
 cell = [[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle 
 reuseIdentifier:CellIdentifier] autorelease];
 }
 
 NSManagedObject *artikel = [fetchedResultsController objectAtIndexPath:indexPath];
 
 //Titel als haupttext der zelle
 cell.textLabel.text= [artikel valueForKey:@"titel"];
 cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
 
 //Autor und Name als Detailtext der Zelle
 NSDateFormatter *dateFormatter = [NSDateFormatter new];
 [dateFormatter setDateStyle:NSDateFormatterMediumStyle];
 NSString *dateString = [dateFormatter stringFromDate:[artikel valueForKey:@"datum"]];
 cell.detailTextLabel.text = [NSString stringWithFormat:NSLocalizedString(@"%@ am %@",nil), [artikel valueForKey:@"autor"], dateString];
 [dateFormatter release];
 return cell;
}

whilst the function fetchedResultsController looks like this.


- (NSFetchedResultsController *)fetchedResultsController
{
 if (fetchedResultsController != nil)
 return fetchedResultsController;
 
 //FetchRequest initialisieren
 NSFetchRequest *fetchedRequest = [NSFetchRequest new];
 NSEntityDescription *artikelDescription = [NSEntityDescription entityForName:@"Artikel" 
 inManagedObjectContext:managedObjectContext];
 [fetchedRequest setEntity:artikelDescription];
 
 NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]initWithKey:@"datum" ascending:NO];
 
 NSArray *sortDescriptors = [[NSArray alloc]initWithObjects:sortDescriptor, nil];
 [fetchedRequest setSortDescriptors:sortDescriptors];
 
 //FetchedResultsController initialisieren
 fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchedRequest 
 managedObjectContext:managedObjectContext 
 sectionNameKeyPath:nil 
 cacheName:@"Overview" ];
 fetchedResultsController.delegate = self;
 //aufräumen
 [fetchedRequest release];
 [sortDescriptor release];
 [sortDescriptors release];
 return fetchedResultsController;
 
}

i'm sorry to bother you with that lot of code.. but i'm stuck here since now 8h,
and wouldnt probably be any step further without your help in the first place,
so thanks a lot for the first inputs =)

Reply

Answer 11

xnav

Level 5

7,089 points

Jan 25, 2011 11:13 AM in response to sfluecki

Humm, I don't see a \[tableView insertRowsAtIndexPaths:] call anywhere?
OR
an update of the array that backs the tableview.

Message was edited by: xnav

Reply

Answer 12

sfluecki Author

Level 1

8 points

Jan 25, 2011 11:40 AM in response to sfluecki

hm woudnt 'cellForRowAtIndexPath' take over this part by setting cell.textLabel and cell.accessoryType?
i'm confused ..

its just the reload/update of the tableview that doesnt work, infact the call [tableView reloadData] seems
to not do anything.

did u look at the whole code? its just 2 files and one tableviewcontroller - here the link to a zip of the
whole xcodeproject: http://www.sflueckiger.ch/data/WeblogClientTouch.zip (save)

Reply

Answer 13

xnav

Level 5

7,089 points

Jan 25, 2011 12:45 PM in response to sfluecki

I'll take a look.

Reply

Answer 14

sfluecki Author

Level 1

8 points

Jan 25, 2011 1:11 PM in response to sfluecki

have a million thanks!
since i'm in another timezone i'm going to sleep now. there's
nothing that'd make me happier than to find an answer tomorrow morning
on which based i could continue to work on this sample and learn more
about iOS, cocoa, etc..

see you tomorrow & thanks again!

Reply

Answer 15

xnav

Level 5

7,089 points

Jan 25, 2011 2:05 PM in response to sfluecki

At the end of (IBAction)neuerArtikel you have to re-fetch.


//Tableview aktualisieren
 if (![self.fetchedResultsController performFetch:&error]) {
 NSLog(@"Hier gab es einen Fehler");
 }
 [self.tableView reloadData];

Reply