Каким образом можно реализовать механизм Copy-on-Write в системе для эффективного управления памятью?

The Copy-on-Write (COW) mechanism allows efficient memory management by delaying the copying of an object until it is modified. Initially, multiple parts of the system can reference the same object. When an attempt is made to modify the object, it is copied, and the changes are applied to the copy.

In iOS, COW can be implemented using a structure with an internal class wrapper that stores data and counts references. For example, in Swift, standard collections (Array, Dictionary) use COW:

class DataStorage {
    var data: [Int]
    init(data: [Int]) {
        self.data = data
    }
}

struct MyArray {
    private var storage: DataStorage

    init(_ elements: [Int]) {
        storage = DataStorage(data: elements)
    }

    mutating func append(_ element: Int) {
        if !isKnownUniquelyReferenced(&storage) {
            storage = DataStorage(data: storage.data) // copying data
        }
        storage.data.append(element)
    }

    var elements: [Int] {
        return storage.data
    }
}

Here, isKnownUniquelyReferenced checks that only one variable references the storage object. If not, a copy is created so that changes do not affect other references. This approach helps save memory and improve performance when working with large data.