Sample Questions with Detailed Answers What is the difference between weak, strong, and unowned references in Swift? Strong references keep a strong hold on the object and increase its reference count. Weak references do not increase the reference count and are set to nil when the referenced object is deallocated, preventing retain cycles. Unowned references do not increase the reference count but are not set to nil when the object is deallocated, which can lead to crashes if not handled properly. How do you handle memory leaks in an iOS application? Use Instruments' Leaks tool to identify memory leaks. Ensure proper use of weak and unowned references to prevent retain cycles. Avoid creating strong reference cycles in closures by using capture lists. Regularly check for and resolve strong reference cycles in the codebase. Can you explain the difference between tableView(_:cellForRowAt:) and collectionView(_:cellForItemAt:)? tableView(_:cellForRowAt:) is used in UITableView to configure and return a cell for a given row at a specified index path. collectionView(_:cellForItemAt:) is used in UICollectionView to configure and return a cell for a given item at a specified index path. UITableView is for single-column, vertically scrolling content, while UICollectionView supports multiple columns and horizontal or vertical scrolling. Describe a situation where you optimized the performance of an iOS application. In a previous project, the app experienced lag during heavy data processing. I optimized the performance by offloading data processing tasks to a background thread using GCD. Additionally, I implemented lazy loading for images and data caching to reduce the load on the main thread, resulting in a smoother user experience. Preparing for the Interview Review Core Concepts: Brush up on Swift, Objective-C, iOS frameworks, and design patterns. Practice Coding: Use platforms like LeetCode, HackerRank, and CodeSignal to practice coding problems. Study System Design: Understand common design patterns and architectures in iOS development. Mock Interviews: Conduct mock interviews to practice your problem-solving and communication skills. Project Review: Be ready to discuss your past projects in detail, highlighting your contributions and the impact.
