Array of dictionary value changes is reflect in all the values - ios

Question

I have NSMutableArray and Added NSMutableDictionary
If i update one value for specific row then all the values changes in NSMutableDictionary.
NSIndexPath *qtyIndex
-(void)demoDefaultCartValues{
[dict_CartItems setValue:#"Item 1 KK Demo" forKey:#"DIC_PRODUCT_NAME"];
[dict_CartItems setValue:#" KK Demo" forKey:#"SELLER_NAME"];
[dict_CartItems setValue:#"1" forKey:#"QTY_VALUE"];
[dict_CartItems setValue:#"42" forKey:#"SIZE_VALUE"];
[dict_CartItems setValue:#"1250" forKey:#"PRICE_VALUE"];
[dict_CartItems setValue:#"1500" forKey:#"DISCOUNT_VALUE"];
for (int i = 0; i <= 5; i++) {
[cartListArray addObject:dict_CartItems];
}
}
#pragma mark - DropDown Delegate
-(void)dropDownView:(UIView *)ddView AtIndex:(NSInteger)selectedIndex{
[[cartListArray objectAtIndex:qtyIndexPath.row] setValue:[sizeArrayList objectAtIndex:selectedIndex] forKey:#"QTY_VALUE"];
NSLog(#"What %#",cartListArray);
}
If I update qty 1 to 5 then all dictionary values QTY_Value changes to 5.

Answer 1

Use new Objective-C features (more than 5 years old) to make this more readable. And add six different mutable dictionaries to the array:
NSDictionary* dict = { #"DIC_PRODUCT_NAME":#"Item 1 KK Demo",
#"SELLER_NAME":#" KK Demo",
#"QTY_VALUE": #"1",
etc.
};
for (NSInteger i = 0; i < 6; ++i)
[cartListArray addObject: [dict mutableCopy]];
and later:
-(void)dropDownView:(UIView *)ddView atIndex:(NSInteger)selectedIndex{
cartListArray [qtyIndexPath.row] [#"QTY_VALUE] = sizeArrayList [selectedIndex];
}
cartListArray should be declared as
NSMutableArray <NSMutableDictionary*> *cartListArray;
Now what I would really recommend that you don't store a dictionary at all, but declare a model class. So you don't have to use strings for quantity etc. but NSInteger. Also that cartListArray isn't mutable if you don't want to modify it after it has been initialised. Keep things immutable whenever you can.

Answer 2

This is obvious
when you are adding NSMutableDictionary to array, array have the reference of that dictionary inside.
Now what you are doing is inserting same dictionary multiple times in array. so when you change a single object in array. all the places are get effected. keeping same object of Dictionary always causes this issue.
Solution for this problem is create a new object every time before you insert into array.
Hope it is helpfult to you

Answer 3

The problem is that your code uses the same dictionary and it's a refrence value , so it's a shallow copy of the same one , you may create a new one every iteration
-(void)demoDefaultCartValues{
for (int i = 0; i <= 5; i++) {
NSMutableDictionary*dict_CartItems = [ NSMutableDictionary new];
[dict_CartItems setValue:#"Item 1 KK Demo" forKey:#"DIC_PRODUCT_NAME"];
[dict_CartItems setValue:#" KK Demo" forKey:#"SELLER_NAME"];
[dict_CartItems setValue:#"1" forKey:#"QTY_VALUE"];
[dict_CartItems setValue:#"42" forKey:#"SIZE_VALUE"];
[dict_CartItems setValue:#"1250" forKey:#"PRICE_VALUE"];
[dict_CartItems setValue:#"1500" forKey:#"DISCOUNT_VALUE"];
[cartListArray addObject:dict_CartItems];
}
}
Or you can use copy / mutableCopy
for (int i = 0; i <= 5; i++) {
[cartListArray addObject:[dict_CartItems mutableCopy]];
}