Objective-C NSMutableArray不添加对象

Question

It seems like I have a problem and don't know if I'm doing this right since I'm just starting objective c.

Right now I have two files

Stores.h

#import<Foundation/Foundation.h>
#import<MapKit/MapKit.h>

@interface Stores: NSObject

@property(nonatomic,strong) NSString *storeName;
@property(nonatomic,strong) NSMutableArray *MenuItems;

@end

Stores.m

#import "Stores.h"

@synthesize storeName,MenuItems;

@end

Menu.h

#import<Foundation/Foundation.h>


@interface Menu: NSObject

@property(nonatomic,strong) NSString *MenuItemDescription;
@property(nonatomic) int MenuItemPrice;

@end

Menu.m

#import "Menu.h"

@synthesize MenuItemDescription,MenuItemPrice;

@end

ViewController.m

#import "ViewController.h"
#import "Stores.h"
#import "Menu.h"

@interface ViewController ()

@end

@implementation ViewController

NSMutableArray *stores;

-(void) viewDidLoad
{
  [super viewDidLoad];

  stores = [[NSMutableArray alloc]init];

  Stores *store = [[Stores alloc]init];

  [store setStoreName:@"Store1"];
  Menu *menuItem = [[Menu alloc]init];
  [menuItem setMenuItemDescription:@"Item1"];
  [menuItem setMenuItemPrice: 7]

  [store.MenuItems addObject:menuItem]; //won't add menuItem to store.MenuItems

  [stores addObject:store]; 

}

@end

So it doesn't end up adding any object to store. If I run it in debug it says that MenuItems has zero objects. I know I'm doing something wrong but like I said I'm new to iOS.

Answer 1

You did not (at least in the code you show) alloc/create/assign MenuItems, so it will still be nil. Calling addObject (or anything) on nil is just a no-op.

Try this

 Stores *store = [[Stores alloc]init];
 store.MenuItems = [NSMutableArray arrayWithCapacity: 10];