moving objects between view controllers

Question

I am new in programming and I have problem with moving objects from one VC to another.

My second VC have NSArray * objects. Third VC have NSMutableArray *products. I have modal segue from 2 -> 3 Here is my segue method:

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if ([segue.identifier isEqualToString:@"Products segue"]) {
     ProductsViewController*pvc = segue.destinationViewController;
     pvc.products = [self.objects mutableCopy];
}

}

In ProductsViewController i create few objects:

-(IBAction)addSomeObjects {
products = [NSMutableArray new];
[products addObject:@"Cola"];
[products addObject:@"Pepsi"];
[products addObject:@"Fanta"];
[products addObject:@"Red bull"];
[products addObject:@"Monster"];

If I NSLog my IBAction method products successfully added my objects but when I dissmissViewController my objects array is empty.

Thanks for any help.

This: `pvc.products = [self.objects mutableCopy]` creates a new mutable array that contains the same objects as `self.objects`. This: `products = [NSMutableArray new]` creates a new empty array. There is nothing in what you've shown that would change `self.objects`. — Phillip Mills, Jul 16 '14 at 17:53
possible duplicate of [Passing Data between View Controllers](http://stackoverflow.com/questions/5210535/passing-data-between-view-controllers) — Hot Licks, Jul 16 '14 at 18:25

score 1 · Accepted Answer · answered Jul 16 '14 at 18:25

M. Koptak. Welcome to programming.

In this example, I would suggest you create a model to manage products. A model is a class that represents data. In this example, create a class to represent the collection of products. For this I will call it a catalog.

// In Catalog.h
@interface Catalog : NSObject
@property (nonatomic, readonly) NSMutableArray *products;
@end

// In Catalog.m
@implementation Catalog
- (id)init
{
    self = [super init];
    if (self) {
        _products = [NSMutableArray array];
    }
}
@end

Now that I have a class which can manage products, I need to have catalog properties (of type Catalog) in both the first view controller and ProductsViewController.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"Products segue"]) {
        ProductsViewController *pvc = segue.destinationViewController;
        pvc.catalog = self.catalog; // Pass the catalog between the view controllers.
    }
}

- (void)viewDidLoad
{
    …
    if (self.catalog == nil) // Make sure an instance of `Catalog` has been created!
        self.catalog = [[Catalog alloc] init];
    …
}

Finally, in ProductsViewController

-  (IBAction)addSomeObjects
{
    [self.catalog.products addObject:@"Cola"];
    [self.catalog.products addObject:@"Pepsi"];
    [self.catalog.products addObject:@"Fanta"];
    [self.catalog.products addObject:@"Red bull"];
    [self.catalog.products addObject:@"Monster"];
}

Now when you dismiss ProductsViewController, the first view controller will have all the new products.

Note: This is the very first step in how to share data. It skips proper class names, data protection, and data validation, but it gets you started.

Thanks for show me better solution. It works fine, but i need that objects in my NSArray :) It work with my search bar so i need fill it with that objects to show that objects in my search bar table view. — M.Koptak, Jul 16 '14 at 18:44
Oh i got it. In viewWillAppear i've put self.objects = self.catalog.products; Now it works finally ! :) many thanks to you — M.Koptak, Jul 16 '14 at 18:59

moving objects between view controllers

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