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iOS Build a Simple iPhone App with Objective-C Creating a Data Model Creating a Data Collection

Posted by James Rowe
James Rowe
2,551 Points

Not understanding what I am doing wrong with question 3 of 3 in 'Creating a Data Collection'

Ive tried a couple of methods, but now I feel I'm just stumbling around in the dark.

ViewController.h 
#import "UIViewController.h"

@interface ViewController : UIViewController

@property (strong, nonatomic) NSString *shoppingCart;
@property (strong, nonatomic) NSArray *shoppingList;

@end
ViewController.m 
#import "ViewController.h"

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Add your code below!

    self.shoppingList = [[NSArray alloc] initWithObjects: @"toothpaste", @"bread", @"eggs", nil];
    self.shoppingCart = [self.shoppingList objectsAtIndex:2];
}

@end

2 Answers

kasaltrix
kasaltrix
9,491 Points

Hi James,

You are almost there at completing your challenge. There is a minor mistake with the method 'objectsAtIndex' which should be replaced by 'objectAtIndex' leading to the correct method call.

self.shoppingCart = [self.shoppingList objectAtIndex:2];

Hope this helps :)

James Rowe
James Rowe
2,551 Points

Thank you so much! That worked... though its frustrating that it was something so simple, after spending so much time on it. Live & learn.

kasaltrix
kasaltrix
9,491 Points

I am glad you figured it out :)

Caleb Kleveter
MOD
Caleb Kleveter
Treehouse Moderator 37,862 Points
Caleb Kleveter
Caleb Kleveter
Treehouse Moderator 37,862 Points

You might need to use an underscore vs. self:

self.shoppingCart = [_shoppingList objectAtIndex:2];
kasaltrix
kasaltrix
9,491 Points

Well you can use the instance variable (ivar) to call a method as mentioned above but I recommend not to use it for that purpose because ivars are basically used for initializing a property under the designated initializer rather than calling class methods. I guess I am going the right way?