Cognizant IOS Developer Interview Questions and Answers

Q1. What is Weak & Unowned , ARC?
Ans. 
Weak & Unowned references are used in ARC to prevent retain cycles in Swift programming.
• Weak references do not increase the retain count of an object, and automatically become nil when the object is deallocated.

• Unowned references do not keep a strong reference to the object, and can become a dangling pointer if the object is deallocated.

• ARC (Automatic Reference Counting) is a memory management system used in Swift to a
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Q2. What is Autoclosure?
Ans. 
Autoclosure is a feature in Swift that automatically wraps an expression in a closure.
• Autoclosure is used to delay evaluation of an expression until it is actually needed.

• It is commonly used with functions that take closures as arguments, allowing the caller to pass in a regular value instead of a closure.

• Autoclosures are created by adding @autoclosure attribute before the closure's parameter type.
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Q3. Code snippets for optional binding, find error ?
Ans. 
Optional binding in Swift helps to safely unwrap optionals and check for nil values.
• Use if let or guard let to safely unwrap optionals and bind the value to a new constant or variable.

• Check for nil values before using the unwrapped value to avoid runtime errors.

• Example: if let name = optionalName { print(name) }

• Example: guard let age = optionalAge else { return }
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Q4. What are Access Controls/modifiers? public vs open?
Ans. 
Access controls/modifiers determine the visibility and accessibility of classes, methods, and properties in object-oriented programming.
• public access control allows a class, method, or property to be accessed from anywhere in the code

• open access control allows a class to be subclassed outside of the module where it is defined

• public is commonly used in Swift for most cases, while open is used when you want to allow subc
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Q5. Protocol vs Closures?
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Protocols define a blueprint of methods, properties, and other requirements that a class or struct must adopt. Closures are self-contained blocks of functionality that can be passed around and used in your code.
• Protocols define a set of methods, properties, and other requirements that a class or struct must implement.

• Closures are self-contained blocks of functionality that can capture and store references to any consta...read more
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Q6. How you use GIT, How to manage conflicts?
Ans. 
I use GIT for version control and manage conflicts by resolving them through communication and collaboration.
• Regularly commit changes to keep track of progress

• Pull latest changes before making any updates to avoid conflicts

• Communicate with team members to resolve conflicts efficiently

• Use tools like Git merge or Git rebase to resolve conflicts

• Document resolution process for future reference
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Q1. Basic interview swift questions (medium to hard)
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Q2. Coding to find correct or whats wrong
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Machine test with collection view and api using url session

Q1. Technical questions of different scenarios
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Q1. Encription and decription in swift
Ans. 
Encryption and decryption in Swift involves using cryptographic algorithms to encode and decode data securely.
• Use common encryption algorithms like AES or RSA for encryption.

• Implement encryption using libraries like CommonCrypto or CryptoSwift.

• Store encryption keys securely and use secure protocols for data transmission.

• Example: Encrypting a string using AES encryption in Swift.
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Q2. Keychain access in swift
Ans. 
Keychain access in Swift allows secure storage of sensitive information like passwords, tokens, etc.
• Use Keychain Services API to securely store and retrieve sensitive data.

• Keychain items are stored securely in the device's keychain and are encrypted.

• Access keychain items using unique identifiers called keys.

• Use Keychain Swift library for easier implementation.
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Q3. Class vs struct
Ans. 
Classes are reference types, while structs are value types in Swift.
• Classes are reference types, meaning they point to the same instance in memory when assigned to a new variable.

• Structs are value types, meaning they create a new copy when assigned to a new variable.

• Use classes for complex data structures or when you need inheritance, use structs for simple data types or when you want value semantics.

• Example: class Per...read more
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Q4. If let and guard let
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Q5. Grand central dispatch in swift
Ans. 
Grand Central Dispatch (GCD) is a technology in Swift for managing concurrent operations.
• GCD allows developers to perform tasks concurrently without having to manage threads manually.

• It provides a high-level API for managing tasks and executing them on different queues.

• Developers can use GCD to perform tasks in the background, update the UI on the main thread, and more.
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Easy aptitude english and logical reasoning.

Q1. Tell me About yourself
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Q2. Swift advantages and disadvantages
Ans. 
Swift is a powerful and modern programming language for iOS development, but it has its own set of advantages and disadvantages.
• Advantages: faster performance, safer code with optionals, easier to read and write code, interoperability with Objective-C

• Disadvantages: steep learning curve for beginners, limited community support compared to other languages like Java or Python
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Q1. Salary expectation and current salary
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Q1. Auto closures and Escaping closures
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Q2. Cardinality and string reverse coding
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Q1. What is closure? Life cycle of escaping closure?
Ans. 
A closure is a self-contained block of code that can be passed around and used in your code. An escaping closure is a closure that is called after the function it was passed to has returned.
• Closure is a block of code that can be passed around and used in your code.

• Escaping closure is called after the function it was passed to has returned.

• Example: Using a completion handler in a network request to handle the response a
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Q2. What is multi threading?
Ans. 
Multi threading is the ability of a CPU to execute multiple threads concurrently, allowing for improved performance and responsiveness in applications.
• Allows for parallel execution of tasks, improving performance

• Enables applications to remain responsive while performing intensive tasks

• Can lead to synchronization issues if not managed properly
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Q1. Arc in swift...
Ans. 
ARC (Automatic Reference Counting) in Swift is a memory management system used to automatically manage memory allocation and deallocation.
• ARC keeps track of how many references there are to an object and automatically deallocates it when there are no more references.

• Use strong reference cycles can lead to memory leaks, so use weak or unowned references to break the cycle.

• ARC is the default memory management system in S...read more
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Q2. Automstic referenc counting
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Q1. Mvvm in swift....
Ans. 
MVVM (Model-View-ViewModel) is an architectural design pattern commonly used in iOS development to separate concerns and improve code maintainability.
• MVVM separates the user interface (View) from the business logic (ViewModel) and data (Model).

• ViewModel acts as an intermediary between the View and the Model, handling user interactions and updating the data.

• Swift provides tools like Combine framework for reactive progra...read more
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Q2. Model view viewmodel
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