How is memory allocated for objects created using reference types?

In iOS, objects created using reference types (e.g., classes) are allocated in dynamic memory (heap). When you create an object, the system allocates memory for it on the heap, and the variable holds a reference to that object.

Memory management in iOS is based on the ARC (Automatic Reference Counting) mechanism. ARC automatically tracks the number of references to an object and frees memory when there are no more strong references to the object.

Example:

class Person {
    var name: String
    init(name: String) {
        self.name = name
    }
}

var person1: Person? = Person(name: "Ivan") // memory allocated on the heap
var person2 = person1 // reference count increases
person1 = nil // the object is still alive because person2 references it
person2 = nil // now the object is released, and memory is returned to the system

Thus, memory for objects is allocated on the heap, and ARC automatically manages the lifetime of objects, freeing memory when it is no longer needed.