[UINavigationController setManagedObjectContext:]: unrecognized selector sent to instance - ios

Question

I know it has been asked multiple times, but the answers won't help solve my problem.
First of all I'm making a Tab based app with CoreData wich opens upon the press of a Button a TableViewController.
The main.storyboard file in case it matters:
http://www.pictureupload.de/originals/pictures/200215153130_Screen_Shot_2015-02-20_at_15.24.09.png
Everything works fine and it saves the data into the Database, but if I try to Display them in a TableViewController it suddenly crashes
(-[UINavigationController setManagedObjectContext:]: unrecognized selector sent to instance 0x79092b80).
AppDelgate.m is just copy and paste from the core Data preset.
Just in case it matters:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
return YES;
}
- (void)applicationWillResignActive:(UIApplication *)application {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
- (void)applicationWillEnterForeground:(UIApplication *)application {
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}
- (void)applicationDidBecomeActive:(UIApplication *)application {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
- (void)applicationWillTerminate:(UIApplication *)application {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
// Saves changes in the application's managed object context before the application terminates.
[self saveContext];
}
#pragma mark - Core Data stack
- (NSURL *)applicationDocumentsDirectory {
// The directory the application uses to store the Core Data store file. This code uses a directory named "controwl.a" in the application's documents directory.
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}
- (NSManagedObjectModel *)managedObjectModel {
// The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
if (_managedObjectModel != nil) {
return _managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"trackingData" withExtension:#"momd"];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
// The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it.
if (_persistentStoreCoordinator != nil) {
return _persistentStoreCoordinator;
}
// Create the coordinator and store
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:#"timetracking.sqlite"];
NSError *error = nil;
NSString *failureReason = #"There was an error creating or loading the application's saved data.";
if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {
// Report any error we got.
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[NSLocalizedDescriptionKey] = #"Failed to initialize the application's saved data";
dict[NSLocalizedFailureReasonErrorKey] = failureReason;
dict[NSUnderlyingErrorKey] = error;
error = [NSError errorWithDomain:#"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict];
// Replace this with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _persistentStoreCoordinator;
}
- (NSManagedObjectContext *)managedObjectContext {
// Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.)
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (!coordinator) {
return nil;
}
_managedObjectContext = [[NSManagedObjectContext alloc] init];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
return _managedObjectContext;
}
#pragma mark - Core Data Saving support
- (void)saveContext {
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
NSError *error = nil;
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
#end
The TableViewController gets called by FirstViewController by the btnBarAdd function:
FirstViewController.m
#implementation FirstViewController
#synthesize context = _context;
- (void)viewDidLoad {
[super viewDidLoad];
_context = [(AppDelegate*)[[UIApplication sharedApplication]delegate] managedObjectContext];
}
- (IBAction)btnBarAdd:(id)sender {
[self performSegueWithIdentifier:#"FirstTableViewSegue" sender:sender];
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:#"FirstTableViewSegue"]) {
[[segue destinationViewController] setManagedObjectContext:_context];
}
}
#end
Any help is appreciated!

Answer 1

The segue links FirstViewController to the Navigation Controller, so the destinationViewController of the segue is the UINavigationController. Hence when you try to set the managedObjectContext on destinationViewController, you get the error.
You need instead to use the topViewController property of the navigation controller, to access the FirstTableViewController itself:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:#"FirstTableViewSegue"]) {
UINavigationController *navCtrl = (UINavigationController *)[segue destinationViewController];
// Assuming the class of your table view controller is "FirstTableViewController"....
// You will need to import the relevant .h file
FirstTableViewController *tableVC = (FirstTableViewController *)navCtrl.topViewController;
[tableVC setManagedObjectContext:_context];
}
}

Answer 2

Check if destination view controller for your code
[[segue destinationViewController] setManagedObjectContext:_context];
Has property or method to assign context. Seems like you are calling UINavigationController with segue but it does not have such property to handle context

Answer 3

Reset the simulator and run it again.
You might have added new properties to the entities, you should delete the app each time you make changes to core data entities.