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This is just a visual scenario of what's actually happening.

I have an Object A in my View Controller1. Similarly, i have an ObjectB which is similar to the type of ObjectA, in my View Controller2.

Now, on click of a button, i assign ViewController2.ObjectB = ViewController1.ObjectA (or self.ObjectA) from my 1st View Controller.

Now, the data passes successfully over to the ViewController2. But, when i perform some changes to ObjectB in ViewController2, the changes are reflected in ObjectA of ViewController1 as well.

This should not happen as the original data of ObjectA is then lost, which i need if user goes to and fro from ViewController1 to ViewController2 and vice-versa as i m always doing this ViewController2.ObjectB = ViewController1.ObjectA on click of my button in ViewController1.

Anybody have any idea what's goin on ? Please help me out. It's driving me nuts :-(

Zahurafzal Mirza
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  • Use a struct instead of a class. Structs have value types. Read more here: https://stackoverflow.com/q/24232799/3151675 – Tamás Sengel Apr 04 '18 at 11:05
  • I m sorry, but i cant use structs as my object classes are being generated by SwiftyJSON. So using struct would mean a big backlog to my entire project. Can you suggest some other alternative ? – Zahurafzal Mirza Apr 04 '18 at 11:08
  • Try implementing a copying method. https://stackoverflow.com/q/24242629/3151675 – Tamás Sengel Apr 04 '18 at 11:11

1 Answers1

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This is happening because your object is passed by reference, not by value. What you can do is to make a clone of your object instead of passing the object itself.

ViewController2.ObjectB = ViewController1.ObjectA.clone()

You have to implement clone function in ObjectA class that is going to create a new object from the current one, something like this

class MyClass {
    let number: Int

    init(number: Int) { 
        self.number = number
    }

    func clone() -> MyClass {
        return MyClass(number: self.number)
    }
}

If you want to know more look up https://developer.apple.com/swift/blog/?id=10 and https://www.raywenderlich.com/112027/reference-value-types-in-swift-part-1

markoaras
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  • i know that it was being passed by reference. I am new to swift so i was a lil bit unsure wether it was happening or not. Thanks to you i finally figured it out. Now i hope your solution works :-D. I am implementing it right now and will let u know – Zahurafzal Mirza Apr 04 '18 at 11:30
  • ok, just be careful about the types of the ObjectA and ObjectB in your case, but I assume you have figured that out since you wrote the `ViewController2.ObjectB = ViewController1.ObjectA` line in your question – markoaras Apr 04 '18 at 11:32
  • the force is strong with you :-D haha..thanks for the solution – Zahurafzal Mirza Apr 06 '18 at 04:16