Context

Memory management is a core part of building reliable iOS features in the American Express Global Business Travel mobile app. Interviewers ask this to assess whether you can prevent leaks, avoid retain cycles, and reason about object lifetimes in Swift.

Core Question

Explain how memory is managed in a Swift app. Your answer should cover:

1. How ARC (Automatic Reference Counting) works under the hood.
2. What causes strong reference cycles, especially between objects and inside closures.
3. When to use weak vs unowned references, and the trade-offs.

Scope Guidance

Go beyond a high-level definition. The interviewer expects you to explain object ownership, deallocation behavior, common leak patterns in UIKit/SwiftUI-style code, and how you would diagnose and prevent memory issues in production code.