1. What is ARC (Automatic Reference Counting)?

Automatic Reference Counting (ARC) is a memory management method utilized in Swift. It is responsible for managing system resources, ensuring that memory allocated to class instances is released when they are no longer in use. ARC tracks the number of references—properties, constants, and variables—each instance has. If there remains at least one reference, ARC will not release that instance.

ARC Functions:

• The init() method is used to create a new instance of a class, allocating the necessary memory to store its information.
• Memory is automatically released when an instance is no longer needed through the deinit() method. ARC ensures that deinit() is called only for instances with no active references.

2. Explain the different types of iOS Application States.

iOS applications can exist in various states:

• Not Running: The app has either not launched or was terminated by the system.
• Inactive: The app is in the foreground but not receiving events, often during transitions such as a phone call.
• Active: The app is fully operational in the foreground, receiving user interactions.
• Background: The app runs code while not in the foreground, allowing for tasks to continue.
• Suspended: The app remains in memory but does not execute any code; it may be purged if the system needs memory.

3. What are different ways to achieve concurrency in iOS?

Concurrency refers to the ability to perform multiple tasks simultaneously, which is crucial for maintaining a responsive user interface while handling background tasks. There are several ways to manage concurrency in iOS:

• Dispatch Queues: These organize tasks in a first-in-first-out manner, allowing for sequential or concurrent execution.
• Threads: Independent sequences of instructions that run separately from the main code, ideal for lengthy tasks.
• Operation Queue Objects: These enable concurrent execution of tasks based on their priority and readiness, providing a higher-level abstraction over GCD.

4. What is the difference between assign and retain keywords?

• Assign: Creates a reference to an object without increasing its retain count, meaning it does not manage the object's memory.
• Retain: Increases the retain count, ensuring that the object remains in memory until it is no longer needed.

5. What are the important features of Swift?

Swift is a modern programming language that emphasizes safety and efficiency:

• Safety: Swift aims to eliminate unsafe code before it is deployed.
• Syntax: It features a clean and straightforward syntax that enhances code readability.
• Multiplatform Support: Swift is compatible across various operating systems including iOS and macOS.
• Open-source: Swift is developed as an open-source language to foster community contributions and improvements.
• Objective-C Compatibility: It allows developers to use Objective-C libraries seamlessly.

6. What do you mean by lazy property in iOS?

Lazy properties are not initialized until they are accessed for the first time. By using the lazy keyword, you can defer the initialization of a property until it's needed, which can simplify code and enhance performance in certain situations.

7. State the difference between strong, weak, read-only and copy.

• Strong: Maintains a reference to an object, preventing it from being deallocated.
• Weak: Allows a reference to an object without increasing its retain count, meaning it can be deallocated if no strong references exist.
• Read-only: A property that can be set initially but cannot be changed afterward.
• Copy: Creates a copy of the assigned object, ensuring that changes to the original do not affect the copy.

8. How can you implement storage and persistence in iOS?

Data persistence involves saving data on disk for future access. Various methods include:

• Data Structures: Use simple structures like arrays and dictionaries.
• Keychain and NSUserDefaults: Provide secure and basic key-value storage.
• NSFileManager: Manages data storage on disk, whether serialized or not.
• Databases: Utilize SQLite for complex data storage and querying.

9. Explain what is GCD (Grand Central Dispatch) in iOS.

Grand Central Dispatch (GCD) is a powerful API for managing concurrent operations in iOS. It allows for efficient background processing, enabling multiple tasks to run simultaneously without blocking the main thread.

10. What is the use of application:willFinishLaunchingWithOptions and application:didFinishLaunchingWithOptions?

Both methods, found in the AppDelegate.swift file, are crucial for initializing the app before its launch. They allow developers to set up necessary configurations and prepare the app for user interaction.

The first video titled "iOS Dev Job Interview - Must Know Topics" covers essential concepts and topics that candidates should familiarize themselves with before their interviews.

The second video "Netflix iOS Interview Question (2022) – Swift" dives into specific interview questions and answers that are relevant for aspiring iOS developers, particularly those looking to work at Netflix.

If you have any questions or need clarification on any topics, feel free to reach out. Thank you for following along; I appreciate your engagement and look forward to making this content valuable for you!