How is the hash value for an object calculated?

In iOS, to compute an object's hash value, the hash method is usually overridden (in Swift — the hashValue property or the hash(into:) method). The hash value is generated based on the object's significant properties to ensure correct behavior in collections like Set or Dictionary. For example, if an object has several properties, their hashes are combined using XOR or other operations.

Example in Swift:

struct User: Hashable {
    var id: Int
    var name: String

    func hash(into hasher: inout Hasher) {
        hasher.combine(id)
        hasher.combine(name)
    }
}

Here, the hash is built from id and name, which allows the object to be uniquely identified.