Can't add object to NSMutableArray from another class - ios

Question

I am trying to add objects to a NSMutableArray from another class and it won't work. It works perfectly for the other attribute.
I looked at similar questions but couldn't find a suitable answer.
The object iPack :
#interface IPack : NSObject
#property float price;
#property NSMutableArray *cocktails;
#end
In the class of my collection view :
- (void)viewDidLoad {
[super viewDidLoad];
self.iPack = [[IPack alloc] init];
self.iPack.cocktails = [[NSMutableArray alloc] init];
In the class of my cell :
self.collectionView.iPack.price = self.price //perfectly works
NSArray* cock = [NSArray arrayWithObjects:c1,c2,c3,c4,c5, nil];
[self.collectionView.iPack.cocktails addObjectsFromArray:cock]; //line won't work

Answer 1

You haven't shown the [IPack init] method, but I strongly suspect you are not allocating the cocktails array. Simply defining it as a property does not mean it's automatically allocated:
#implementation IPack
- (instancetype)init
{
self = [super init];
if (self) {
_price = 0.0f;
_cocktails = [NSMutableArray new];
}
return self;
}
#end
EDIT
I've just seen this line in your question:
self.iPack.cocktails = [[NSMutableArray alloc] init];
Which would suggest my answer is wrong (despite it being the better way of doing the same thing). Sorry about that; I cannot see why your code doesn't work. Are you sure you are checking correctly?

Answer 2

try this,
in IPack class add a method
#interface IPack : NSObject
#property float price;
#property NSMutableArray *cocktails;
- (instancetype)initWithPrice:(float)price cocktails:(NSMutableArray *)cocktails;
#end
and in implementation
#implementtion IPack
- (instancetype)initWithPrice:(float)price cocktails:(NSMutableArray *)cocktails {
self = [super init];
if (self) {
self.price = price;
self.cocktails = cocktails;
}
}
#end
In the class of my collection view :
remove alloc init in viewDidLoad
that is remove the following lines
self.iPack = [[IPack alloc] init];
self.iPack.cocktails = [[NSMutableArray alloc] init];
In the class of my cell :
NSArray* cock = [NSArray arrayWithObjects:c1,c2,c3,c4,c5, nil];
IPack *ipack = [[IPack alloc] initWithPrice:self.price cocktails:[NSMutableArray arrayArray:cock]];
self.collectionView.iPack = ipack;