How is memory management implemented in the iOS operating system?

Memory management in iOS is based on the ARC (Automatic Reference Counting) model — an automatic reference counting system. Each object in memory has a reference count that increases when a new reference to the object is created and decreases when the reference is removed. When the count reaches zero, the object is automatically deallocated.

Features of memory management in iOS:

• ARC relieves developers from manually calling retain/release.
• Strong references increase the count, weak references do not, which helps avoid retain cycles.
• There are tools for tracking memory leaks, such as Instruments with Leaks and Allocations.
• In addition to ARC, iOS uses virtual memory and OS memory management mechanisms to optimize resource usage.

Example of a weak reference in Swift:

class Person {
    var name: String
    weak var friend: Person? // weak reference to avoid retain cycle

    init(name: String) {
        self.name = name
    }
}

Thus, iOS combines automatic reference counting with system memory management mechanisms for efficient application performance.