Kuidas algab viidete hoidmise tsükkel hallatavates programmeerimiskeeltes?

In languages with automatic memory management, such as Swift or Objective-C on iOS, a retain cycle occurs when two or more objects hold strong references to each other, preventing the garbage collector or ARC (Automatic Reference Counting) from releasing these objects.

A retain cycle begins, for example, when object A has a strong reference to object B, and object B, in turn, has a strong reference to object A. This causes the reference counts of both objects to never reach zero.

To prevent such cycles, the following are used:

• Weak references (weak) — do not increase the reference count and are automatically set to nil when the object is deallocated.
• Unowned references (unowned) — do not increase the count, but are not automatically set to nil, used when the object is guaranteed to exist longer.

Example:

class Person {
    var apartment: Apartment?
}

class Apartment {
    weak var tenant: Person?  // weak reference to avoid cycle
}

This way, the retain cycle is initiated through mutual strong references, and is prevented by using weak or unowned references to break the cycle.