How to make a copy of a swift array of class objects

Question

In code below, list1 is original Array. when i copy list1 in list2, it passes "allCardList" array as reference but i want to create copy of list1 so when i change in list2 it shouldn't change original Array (list1)

class Card {
    var availableBalance        = "5"
}
class DataCacheManager: NSObject {
    var allCardList             = [Card]()
}
var card = Card()
card.availableBalance = "10"

var list1 = DataCacheManager()
list1.allCardList.append(card)

var list2 = DataCacheManager()

for item in list1.allCardList {
    list2.allCardList.append(item)
}

list2.allCardList[0].availableBalance = "20"

print(list1.allCardList[0].availableBalance) // print 20 but should return 10

Any help you that?

Of course it will print 20 since you are changing the reference object. You need to deep copy you array if you want to have different values. — Gihan, Jul 05 '17 at 14:28

score 2 · Answer 1 · answered Jul 05 '17 at 14:28

2

A class has reference semantics. The simplest solution is to use value semantics

struct Card ...

answered Jul 05 '17 at 14:28

vadian

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score 0 · Answer 2 · answered Jul 05 '17 at 14:28

0

Take a look at this question, it describes the process of copying a single object.

Implementing copy() in Swift

After you added the ability of copying, iterate through your array with a for loop to create a copied array from your existing data.

answered Jul 05 '17 at 14:28

Tamás Sengel

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score 0 · Answer 3 · answered Jul 05 '17 at 14:34

Please read these references How do I make a exact duplicate copy of an array?1 and deep copy array In you case there other ways to achive your requirement without copying the whole array. For a example you could have an readonly original value as a object in Card and have another variable for the new value and so on.

How to make a copy of a swift array of class objects

3 Answers3