Kuidas operatsioonisüsteem määrab, millal objekt mälus enam ei kasutata ja seda saab ohutult vabastada?

The operating system itself does not directly manage the release of objects in memory — this is the responsibility of the runtime environment and the programming language. For example, in iOS, memory management is performed using the ARC (Automatic Reference Counting) mechanism.

ARC tracks the number of references to an object. When the reference count of an object reaches zero (meaning no one else is referencing it), the object is automatically released from memory.

Example:

class MyClass {}
var obj: MyClass? = MyClass() // reference count = 1
obj = nil // reference count = 0, object is released

Thus, the operating system does not determine when an object is no longer in use — this is done by the runtime environment through reference counting or garbage collection.