What is ARC (Automatic Reference Counting) and how does it work?

ARC is Swift's memory management system that automatically tracks and manages memory usage.\n\n• **How ARC Works:**\n• Tracks number of references to each class instance\n• Automatically deallocates instances when reference count reaches zero\n• Works at compile time, not runtime\n• No performance overhead during execution\n\n• **Reference Types:**\n• **Strong:** Default reference type, keeps object alive\n• **Weak:** Doesn't keep object alive, becomes nil when deallocated\n• **Unowned:** Doesn't keep object alive, assumes object exists\n\n• **Retain Cycles:**\n\nclass Person { \n var apartment: Apartment?\n}\n\nclass Apartment { \n let tenant: Person\n init(tenant: Person) {\n self.tenant = tenant\n }\n}\n\n\n• **Best Practices:**\n• Use weak for delegate patterns\n• Use unowned when you're certain the reference won't be nil\n• Avoid strong reference cycles