Question

I’m using storyboard and XCode 4.3 to create an app that has a tab bar as root view. Even though my app has other segues that work just fine, one of them just does not trigger. It’s supposed to trigger when the third item of the tab is selected. The only thing I can see is that the tab bar actually loads the new view, but no information is passed.

The connections on Storyboard are as follow : Root View controller (Tab bar) -> Navigation Controller -> CapitolDetailViewController (which has a push segue from another view controller)

I’ve tried many changes in the connections, code, etc. But it just doesn’t trigger this segue. I tried to change the code in my AppDelegate to add the new controllers that were missing. The code for my applicationDidFinishLaunching is the following:

NSManagedObjectContext *context = [self managedObjectContext];


NSError *error;
if (![context save:&error]) {
    NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
}

    tabBarController = (UITabBarController *)self.window.rootViewController;


    UINavigationController *view1 = [[tabBarController viewControllers]    objectAtIndex:0];
    UINavigationController *view2 = [[tabBarController viewControllers] objectAtIndex:1];
    UINavigationController *view3 = [[tabBarController viewControllers] objectAtIndex:2];

    SCDMasterViewController *view11 = [[view1 viewControllers] objectAtIndex:0];
    view11.managedObjectContext = self.managedObjectContext;    

    SerieDetailViewController *view22 = [[view2 viewControllers] objectAtIndex:0];

    CapitolDetailViewController *view33 = [[view3 viewControllers] objectAtIndex:0];


    return YES;

Where “SerieDetailViewController” is the one that should pass the information when the 3rd item is selected, and “CapitolDetailViewController” is the one that should receive it.

Code for my segue: (it doesn’t even enter the segue, de NSLOG never shows up)

    - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {


    NSLog(@"Entra segue");


    if ([segue.identifier isEqualToString:@"mostraCapitol"]) {



        NSString *nom = @"";

        nom= serieName;

        CapitolDetailViewController *destViewController = segue.destinationViewController;

        destViewController.serieName2 = nom; 

    }
}

Anyone knows what is wrong?

UPDATE: even though I received an answer that helped me to correct some compilation errors, the problem is still there. If I click the tab bar item, it loads an empty view. It never calls the segue. It looks like the tab bar items and the view controllers are not attached.

Answer 1

Try checking the segue method that does not work. Make sure your identifier for the segue in the storyboard mach the one in your class. From the look of your code and all the comments it seems that your code is fine and should work. The only place that might give you an issue would be different identifiers for the segue in storyboard. I hope this resolves your issue my friend.

Edit:

well i don’t know if this works for you but i have a different approach in setting up the core data in tab bar app. in .h file of the delegate almost everything is generic, in .m particularly applicationdidfinishwithoption i use index number in order to sort the views in view controller that i add to tab bar. i hope this helps, here is the code i use.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
[self setupFetchedResultsController];

if (![[self.fetchedResultsController fetchedObjects] count] > 0 ) {
NSLog(@"!!!!! ~~> There's nothing in the database so defaults will be inserted");
[self importCoreDataDefaultRoles];
}
else {
NSLog(@"There's stuff in the database so skipping the import of default data");    
}

// The Tab Bar
UITabBarController *tabBarController = (UITabBarController *)self.window.rootViewController;

// The Two Navigation Controllers attached to the Tab Bar (At Tab Bar Indexes 0 and 1)
 UINavigationController *view1 = [[tabBarController viewControllers] objectAtIndex:0];
UINavigationController *view2 = [[tabBarController viewControllers] objectAtIndex:1];

View1 *view1 = [[view1nav viewControllers] objectAtIndex:0];
personsTVC.managedObjectContext = self.managedObjectContext;    

View2 *view2 = [[view2nav viewControllers] objectAtIndex:0];
rolesTVC.managedObjectContext = self.managedObjectContext;

return YES;
}

by using index numbers i was able to achieve the same scenario without any error and for the start up view i used a child that i plugged in as initial modal view. hope this helps you. in my case core data was to be added to multiple tabs, i do not know if you have the same need.

EDIT 1

here is my Appdelegate.h

#import <UIKit/UIKit.h>
#import <CoreData/CoreData.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator   *persistentStoreCoordinator;
@property (strong, nonatomic) NSFetchedResultsController *fetchedResultsController;

- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;

@end

and here is the app delegate.m

#import "AppDelegate.h"

#import "PersonsTVC.h"
#import "RolesTVC.h"

@implementation AppDelegate

@synthesize window = _window;
@synthesize managedObjectContext = __managedObjectContext;
@synthesize managedObjectModel = __managedObjectModel;
@synthesize persistentStoreCoordinator = __persistentStoreCoordinator;
@synthesize fetchedResultsController = __fetchedResultsController;

- (void)insertRoleWithRoleName:(NSString *)roleName
{
Role *role = [NSEntityDescription insertNewObjectForEntityForName:@"Role"
                                              inManagedObjectContext:self.managedObjectContext];

role.name = roleName;

[self.managedObjectContext save:nil];
}

- (void)importCoreDataDefaultRoles {

NSLog(@"Importing Core Data Default Values for Roles...");
[self insertRoleWithRoleName:@"Player 1"];
[self insertRoleWithRoleName:@"Player 2"];
[self insertRoleWithRoleName:@"Player 3"];
[self insertRoleWithRoleName:@"Player 4"];
[self insertRoleWithRoleName:@"Player 5"];
[self insertRoleWithRoleName:@"Player 6"];
[self insertRoleWithRoleName:@"Player 7"];
[self insertRoleWithRoleName:@"Player 8"];
[self insertRoleWithRoleName:@"Player 9"];
[self insertRoleWithRoleName:@"Player 10"];
[self insertRoleWithRoleName:@"Player 11"];
[self insertRoleWithRoleName:@"Player 12"];
NSLog(@"Importing Core Data Default Values for Roles Completed!");
}
- (void)setupFetchedResultsController
{
// 1 - Decide what Entity you want
NSString *entityName = @"Role"; // Put your entity name here
NSLog(@"Setting up a Fetched Results Controller for the Entity named %@", entityName);

// 2 - Request that Entity
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:entityName];

// 3 - Filter it if you want
//request.predicate = [NSPredicate predicateWithFormat:@"Person.name = Blah"];

// 4 - Sort it if you want
request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor   sortDescriptorWithKey:@"name"
                                                                             ascending:YES
                                                                                selector:@selector(localizedCaseInsensitiveCompare:)]];
// 5 - Fetch it
self.fetchedResultsController = [[NSFetchedResultsController alloc]    initWithFetchRequest:request
                                                                  managedObjectContext:self.managedObjectContext
                                                                  sectionNameKeyPath:nil
                                                                           cacheName:nil];
[self.fetchedResultsController performFetch:nil];
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
[self setupFetchedResultsController];

if (![[self.fetchedResultsController fetchedObjects] count] > 0 ) {
NSLog(@"!!!!! ~~> There's nothing in the database so defaults will be inserted");
[self importCoreDataDefaultRoles];
}
else {
NSLog(@"There's stuff in the database so skipping the import of default data");    
}

// The Tab Bar
UITabBarController *tabBarController = (UITabBarController *)self.window.rootViewController;

// The Two Navigation Controllers attached to the Tab Bar (At Tab Bar Indexes 0 and 1)
UINavigationController *personsTVCnav = [[tabBarController viewControllers]  objectAtIndex:0];
UINavigationController *rolesTVCnav = [[tabBarController viewControllers] objectAtIndex:1];

// The Persons Table View Controller (First Nav Controller Index 0)
PersonsTVC *personsTVC = [[personsTVCnav viewControllers] objectAtIndex:0];
personsTVC.managedObjectContext = self.managedObjectContext;    

// The Roles Table View Controller (Second Nav Controller Index 0)
RolesTVC *rolesTVC = [[rolesTVCnav viewControllers] objectAtIndex:0];
rolesTVC.managedObjectContext = self.managedObjectContext;

//NOTE: Be very careful to change these indexes if you change the tab order

// Override point for customization after application launch.
// UINavigationController *navigationController = (UINavigationController *)self.window.rootViewController;
// RolesTVC *controller = (RolesTVC *)navigationController.topViewController;
// controller.managedObjectContext = self.managedObjectContext;
return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application
{
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
}

- (void)applicationDidBecomeActive:(UIApplication *)application
{
}

- (void)applicationWillTerminate:(UIApplication *)application
{
[self saveContext];
}

- (void)saveContext
{
NSError *error = nil;
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != 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();
} 
}
}

#pragma mark - Core Data stack

- (NSManagedObjectContext *)managedObjectContext
{
if (__managedObjectContext != nil)
{
return __managedObjectContext;
}

NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil)
{
__managedObjectContext = [[NSManagedObjectContext alloc] init];
[__managedObjectContext setPersistentStoreCoordinator:coordinator];
}
return __managedObjectContext;
}
- (NSManagedObjectModel *)managedObjectModel
{
if (__managedObjectModel != nil)
{
return __managedObjectModel;
}
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Model" withExtension:@"momd"];
__managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
return __managedObjectModel;
}

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if (__persistentStoreCoordinator != nil)
{
return __persistentStoreCoordinator;
}

NSURL *storeURL = [[self applicationDocumentsDirectory]    URLByAppendingPathComponent:@"StaffManager.sqlite"];

NSError *error = nil;
__persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc]    initWithManagedObjectModel:[self managedObjectModel]];


NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                     [NSNumber numberWithBool:YES],    NSMigratePersistentStoresAutomaticallyOption,
                     [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType   configuration:nil URL:storeURL options:options error:&error])
{
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}    

return __persistentStoreCoordinator;
}

#pragma mark - Application's Documents directory


- (NSURL *)applicationDocumentsDirectory
{
return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}

@end

now bare in mind that i use both classes for for data entities and declared the managed objects in both classes. one thing is for sure when using core data your initial view has to have the managed objects. if this does not help you then i sugest you can take a look at tim roadley’s core data tutorial or paul hagurty’s stanford core data class. if you need a whole project to look at let me know and ill try to get something together and place a link so you can download it, but i believe if you have created a proper model and are using the right methods in app delegate similar to what i did, it should work. hope this helps you my friend.