Question

I present a UINavigationController as a ModalViewController. The UINavigationViewController handles a segue of (navigated) UIViewControllers. With my first ModalViewController (MVC) I want to create a new instance of my NSObject which has several properties. This works.

Now in every VC I have a slider to change one of the several properties of my object. At the last VC I want to save the object.

I’m using CoreData (which already works when I work with all of the properties in one VC).

Is there an easy way to achieve this?

(I’m also using NSNotificationCenter.)

EDIT:

• In MVC1 I send a NSNotification to DetailTableViewController by pressing Next in my UINavigationBar. MVC1 pushes to MVC2.

• When DTVC receives the NSNotification it does self insertNewObject: (standard Apple CoreData method) This methods works, I see a new instance of the object in my UITableView after dismissing the MVControllers.

• MVC2 has an UISlider which value I want to store in my object. So I did #import "Object.h", @property (nonatomic, weak) Object * detailItem, @sythesize detailItem and stored a certain value using detailItem.property = NSNumber initWithInt etc.. I press Next. MVC2 pushes to MVC3.

• MVC3 has also #imported ... and @property .... It does in viewDidLoad: NSLog(@"%i", [detailItem.property intValue]); and shows 0 instead of myInteger. What am I doing wrong?

EDIT:

Which changes are necessary to make this piece of code work?

In ModalViewController

- (void)setDetailItem:(Object *)newDetailItem
{
if (_detailItem != newDetailItem) {
    _detailItem = newDetailItem;

    // Update the view.
    [self configureView];
}
}

In MasterViewController

- (void)insertNewObject
{
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];

[newManagedObject setValue:@"New Object" forKey:@"name"];
[self.firstAssistantViewController setDetailItem:(Object *)newManagedObject];

// Save the context.
NSError *error = nil;
if (![context save:&error]) {
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
}
}

Answer 1

Pass the new object along as a property to the other modal view controllers. The managed object contains a reference to the managed object context so you can save at any point.

So, for each modal view controller:

.h:

@property (nonatomic,weak) Object* newManagedObject;

.m:

@synthesize newManagedObject;

And before you present each view controller:

modalViewControllerX.newManagedObject = newManagedObject;

Configure your UI (set the slider values etc) on viewWillAppear: like so:

self.slider.value = self.newManagedObject.property;

And update the managed object using the reverse when the slider value changes:

self.newManagedObject.property = self.slider.value;

In the final view controller, if you wish to save there, you can do this:

NSError *error = nil;
[self.newManagedObject.managedObjectContext save:&error];
// Your own error checking goes here