How is memory allocation and deallocation handled for reference data types?

In iOS, for reference types (such as classes), memory is allocated dynamically on the heap. When a class object is created, the system allocates memory for it on the heap and returns a reference to that object.

Memory is freed using Automatic Reference Counting (ARC). Each object maintains a reference count — the number of active references to it. When a new reference is created, the count increases; when a reference is removed or set to nil, the count decreases. When the count reaches zero, the object is automatically removed from memory.

Example:

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

var person1: Person? = Person(name: "Ivan") // reference count = 1
var person2 = person1 // reference count = 2
person1 = nil // reference count = 1
person2 = nil // reference count = 0, Person object is removed from memory

Thus, developers do not need to manually free memory — ARC manages this automatically.