Getting a copy of an instance of NSManagedObject class in swift

Question

I have an instance of Addon class (inherited from NSManagedObject) foundSampleAddon. I want to create a copy of this instance of class and mutate its properties. I am trying to copy this instance using the following code but I am not sure how to achieve it as I am getting an exception

-[Addon copyWithZone:]: unrecognized selector sent to instance 0x7f9d1d805000

I dont know how to create copy of this instance of class using the copyWithZone: function. I have posted the code below where I am trying to copy foundSampleAddon into a new identity, sampleAddonToAdd and then changing its property productAddonPrice.

if let sampleAddonToAdd = foundSampleAddon.copy() as? Addon {
        if addonCategoriesSent![sentIndexPath!.section].replacePreviousBasePrice == 1 {
             sampleAddonToAdd.productAddonPrice = NSNumber(int: 0)
        }
        addonsToAddBackToProduct.append([keyAnAddon: sampleAddonToAdd, keyAddonCount: 1])
}

score 1 · Answer 1 · edited May 23 '17 at 12:30

1

NSManagedObject does not conform to the NSCopying protocol. If you want to create a new record with the same data, just insert a new object and assign the values from the first object to the second object.

As said here

edited May 23 '17 at 12:30

Community

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answered Dec 02 '15 at 18:02

Tancrede Chazallet

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score 0 · Answer 2 · answered Dec 02 '15 at 15:42

0

You have to create a second NSManagedObject and copy the properties.

let sampleAddonToAdd = NSEntityDescription.insertNewObjectForEntityForName("Addon", inManagedObjectContext: self.managedObjectContext) as! Addon
sampleAddonToAdd.productAddonPrice = foundSampleAddon.productAddonPrice.copy() // copy properties

Then modify the properties you want to.

answered Dec 02 '15 at 15:42

orkoden

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This initilization wont have properties of foundSampleAddon saved in it, which i want to achieve. I want a copy and not an initialization – Ishaan Sejwal Dec 02 '15 at 15:53
You have to make the copy yourself is what I'm saying. Copying all the properties gets you a copy of the object. – orkoden Dec 03 '15 at 10:51
but some of the properties of the class itself are reference to another class, what to do about them? – Ishaan Sejwal Dec 03 '15 at 10:53
You mean reference to a different instance? You can copy references just fine. – orkoden Dec 03 '15 at 10:54
sorry i meant instances of another class. If i copy them, any mutation to it will be reflected in both `Addon` objects – Ishaan Sejwal Dec 03 '15 at 10:57
If you want to deep copy a whole data structure, you will have to implement your own copy methods, that also create copies of referenced objects. – orkoden Dec 03 '15 at 11:53
thanks for the help, but i am going to make a workaround. – Ishaan Sejwal Dec 04 '15 at 05:14
It would be nice if you post your solution here. – orkoden Dec 04 '15 at 10:11

Getting a copy of an instance of NSManagedObject class in swift

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