iOS interview questions

List of iOS interview question which collected from real world interviews

The Concurrency

• How do we achieve concurrency in iOS
• What is GCD
• Explain sync and async
• Ever face any race condition in iOS. Explain with example
• What is DispatchQueue
• Explain sync and async of DispatchQueue
• Types of DispatchQueues
• What is quality of services
• Explain a scenario where we can use DispatchGroup
• What is DispatchWorkItem
• Why we need Operations
• Predict output of the codes
• Explain semaphore in Swift
• What is target quenes in iOS

Memory Management

• Please explain memory management in iOS
• What is ARC. Explain the working
• What is strong references
• Will ARC only works with classes?
• Explain memory leak in iOS
• How do we find memory leak in iOS
• What is weak and unowned. Explain the difference
• What are the best practices you can use to handle memory management in iOS?
• When to use unowned

The Debugging

• Explain your experinece in with debugging
• What is LLD
• How do we test the low network scenario in iOS
• How do you track crash happened in production

Custom types

• Difference between Struct and Class
• How do we choose between class and structure
• Is array refernce type or value stype? What about strings?
• What is copy on write
• What is value type and reference type
• Stack vs heap allocation
• What kind of memory allocation is used for struct and why

The performance

• How would you optimize the performance and scrolling smoothness of the table view? #7

The protocols

• How to create a generic protocol in Swift #13
• What is Protocol - Composition and Protocol - Extension
• How how to give default implementation for protocol methods

The core

• Explain the design principle that you follows while developing a software #12
• Design patterns used in development

The Access control

• Difference between fileprivate and private
• Explain access control in swift
• Difference between internal and public
• Difference between open and public

The Extension

• Advantage of using extensions
• Can we create a stored property in extension and how we can create it

The Closure

• Explain closure and types
• What is capture list in Swift? Explain with example
• Explain the difference between Escaping and Non-Escaping Closures in Swift
• Is closure reference type

The Optionals

• What is the type of optional in Swift? How are they used and why are they significant
• Explain optionals unwrapping
• How do you handle absense of a value in Swift
• What is Optional binding and optional chaining
• If optionals are not there, How would you create one

The Generics

• What is generics
• How do we create a generic func which only works with a particular type in Swift
• Can we create generic protocols

The System Design

Asking relevent question to interviewer is the key when it comes to system design

• How do you create an Authentication module
• Design a news app with two screens

The Behaviour

• What do you check in the PR reviews
• What is your thoughts on using third party libraries
• A challenging situation in last 6 months
• Why did you left the previous company
• What motivates you to work at current company
• Why are you leaving the current company
• Why should we hire you
• Role and responsibilities
• What are your expectaions for next role
• How do you resolve conflict with a collegue
• Share a situation when you were under pressure
• Share a situation where you take risk
• Share an experience about a failure