iOS Developer Interview Roadmap

A step-by-step path through the topics that iOS interviews test. Start at the top and work down. Every topic links to questions you can practice now.

1. 1

   Swift fundamentals

   0/7 learned

   The language basics that every iOS interview checks. Learn these well before you move on.

   Value and reference types

   Structs and enums are value types. Classes are reference types. Interviewers ask this first because it affects memory, threads and how you design models.

   0/3

   Optionals

   An optional holds a value or nil. Interviewers want to see that you unwrap safely and never crash on nil.

   0/1

   Enums and pattern matching

   Swift enums can carry data in each case. They are a great way to model states like loading, loaded and failed.

   0/1

   Closures

   A closure is a block of code you can pass around. It can capture variables from the code around it. Many memory bugs start here.

   0/3

   Error handling

   Swift uses throws, try and catch for errors. Interviewers check that you know when to throw and when to return a Result.

   0/1

   Properties and access control

   Swift has stored, computed, lazy and static properties. Access control decides who can see your code. These are common warm-up questions.

   0/4

   Property wrappers, result builders and macros

   These features remove repeated code. SwiftUI uses all three. Senior interviews may ask how they work inside.

   0/4
2. 2

   Protocols and generics

   0/5 learned

   Swift code is built on protocols. Generics let you write one piece of code that works for many types.

   Protocol-oriented programming

   A protocol describes what a type can do. Protocol extensions add shared behavior. Interviewers like to compare this with class inheritance.

   0/1

   Equatable, Hashable and Comparable

   These protocols let you compare and sort your types. They also let you use them in sets and as dictionary keys. Swift can often write the code for you.

   0/2

   Generics

   Generics let one function or type work with many types and stay type-safe. Most data structure tasks in interviews are generic.

   0/2

   Associated types, some and any

   An associated type is a placeholder type inside a protocol. The keywords some and any decide how you use such a protocol. This is a common senior question.

   0/2

   Method dispatch

   Dispatch is how Swift finds which method to call. Static dispatch is fast. Dynamic dispatch is flexible. Interviewers use this to test deep Swift knowledge.

   0/2
3. 3

   Memory management

   0/5 learned

   Swift uses ARC to free memory. You must know how it works and how to stop leaks.

   How ARC works

   ARC counts the strong references to each class instance. When the count goes to zero, the object is freed. Interviewers expect a short, clear explanation.

   0/2

   Strong, weak and unowned

   Each reference can be strong, weak or unowned. The choice decides if an object stays alive. A wrong choice causes a leak or a crash.

   0/1

   Retain cycles

   A retain cycle happens when two objects hold each other strongly. Neither one is ever freed. This is one of the most asked iOS questions.

   0/3

   Finding memory leaks

   Knowing what a leak is is not enough. You must show how you find one in a real app.

   0/2

   Memory-aware caches

   A cache trades memory for speed. A good cache has a limit and removes old items. Building one is a popular coding task.

   0/2
4. 4

   Concurrency

   0/7 learned

   Apps do work in the background and keep the UI smooth. Expect deep questions here, from GCD to Swift 6.

   GCD and operation queues

   GCD runs work on queues. Many apps still use it, so interviewers ask about it next to async/await.

   0/2

   async/await

   async/await lets you write async code that reads like normal code. It is the main way to do async work in modern Swift.

   0/3

   Tasks and structured concurrency

   A task is a unit of async work. Task groups run many tasks in parallel. Cancellation is cooperative, so your code must check for it.

   0/3

   Actors and the main actor

   An actor protects its state so only one task uses it at a time. @MainActor keeps UI code on the main thread.

   0/3

   Thread safety

   A data race happens when two threads change the same data at the same time. Interviewers want to see that you can find and fix these bugs.

   0/3

   Sendable and Swift 6

   Swift 6 checks for data races when you compile. Sendable marks types that are safe to share between threads.

   0/2

   Debounce, throttle and Combine

   Many UI tasks need control over time, like search as you type. Small helper types and Combine solve this. These are popular practical tasks.

   0/4
5. 5

   UIKit

   0/5 learned

   Most large apps still use UIKit. Interviewers expect you to know its lifecycle, layout and lists.

   View controller lifecycle

   A view controller goes through steps like load, appear and disappear. You must know what work belongs in each step.

   0/1

   Views and Auto Layout

   Every screen is a tree of views placed by constraints. Interviewers test frame vs bounds and how the layout pass works.

   0/4

   Table and collection views

   Lists are in almost every app. Cell reuse keeps them fast. Diffable data sources make updates safe and animated.

   0/4

   Delegation

   The delegate pattern lets one object hand work to another. UIKit uses it everywhere.

   0/1

   Responder chain and the view tree

   Hit-testing finds the view that was touched. Events then move up the responder chain. Some interviews ask you to code tree problems on the view hierarchy.

   0/3
6. 6

   SwiftUI

   0/5 learned

   SwiftUI is the default for new screens. Know how state drives the UI and how SwiftUI decides what to redraw.

   State management

   In SwiftUI the UI is a function of state. You must pick the right tool for each piece of state.

   0/3

   View identity and lifecycle

   SwiftUI tracks each view by its identity. When the identity changes, the state resets. This explains many strange bugs.

   0/3

   Navigation

   NavigationStack uses data to drive navigation. This makes deep links and state restore easier.

   0/1

   SwiftUI performance

   SwiftUI is fast when views stay small and cheap. Slow screens usually redraw too much or do work inside body.

   0/1

   SwiftUI and UIKit together

   Real apps mix SwiftUI and UIKit. You should know how to put one inside the other.

   0/1
7. 7

   Architecture

   0/5 learned

   Good structure makes an app easy to change and test. Interviewers want to hear trade-offs, not one best pattern.

   MVC, MVVM, VIPER and TCA

   Each pattern splits the code in a different way. Know the pros and cons of each one and when you would pick it.

   0/1

   Dependency injection

   Dependency injection means you pass in what an object needs. It makes code easy to test and easy to change.

   0/3

   Coordinators and routing

   A coordinator moves navigation out of view controllers. A router turns a URL into a screen.

   0/2

   Modularization with SPM

   Big apps split code into modules. Modules build faster and keep features apart.

   0/2

   Decoupled communication

   Parts of an app often need to talk without knowing each other. An event bus can do this. Use it with care, because hidden flows are hard to debug.

   0/1
8. 8

   Networking

   0/6 learned

   Almost every app talks to a server. Expect questions on requests, JSON, caching and errors.

   URLSession

   URLSession sends requests and gets data back. With async/await, a request takes only a few lines.

   0/1

   Codable and JSON

   Codable turns JSON into Swift types and back. Interviewers test edge cases like missing keys and different names.

   0/2

   Building a networking layer

   A good networking layer hides URLSession behind a small protocol. It handles errors, retries and auth in one place.

   0/2

   HTTP and image caching

   Caching makes apps faster and saves data. You should know both HTTP caching and in-memory image caching.

   0/2

   Pagination

   Long lists load one page at a time. You must avoid duplicate requests and stop at the last page.

   0/2

   REST, GraphQL and WebSockets

   Each API style fits a different need. Interviewers want you to pick one for a feature and say why.

   0/1
9. 9

   Persistence

   0/4 learned

   Apps save data on the device. Know which storage to pick and how to use it safely.

   Choosing storage

   iOS has many ways to save data. Pick one based on the size and type of data, and how secret it is.

   0/1

   Core Data

   Core Data is Apple's framework for storing object graphs. The hard part is using it safely from many threads.

   0/1

   SwiftData

   SwiftData is the modern Swift API for storing models. It uses macros and works well with SwiftUI.

   0/1

   Offline-first apps

   An offline-first app saves data locally first and syncs later. This is a common system design topic.

   0/1
10. 10

    App lifecycle and platform

    0/5 learned

    Your app runs inside iOS. Know how the system starts, pauses and wakes it up.

    App and scene lifecycle

    An app moves between states like active, background and suspended. Scenes let one app have many windows.

    0/1

    Background work

    iOS limits background work to save battery. You must know which API fits each job.

    0/1

    Push notifications

    Push notifications come from your server through APNs. Interviewers ask about the full flow, from device token to tap.

    0/1

    Universal links and deep links

    A universal link opens your app from a normal web URL. The app must then show the right screen.

    0/2

    Accessibility

    Accessibility makes your app usable for everyone. Good interviewers check it in UI rounds.

    0/2
11. 11

    Testing

    0/4 learned

    Interviewers want to know that you write tests and design code that is easy to test.

    Unit testing

    A unit test checks one small piece of logic. Know both Swift Testing and XCTest.

    0/1

    Mocks and test doubles

    To test one type alone, you replace its dependencies with fakes. This only works if you inject them.

    0/2

    Testing time-based code

    Code that waits, like debounce or retry, is hard to test. Inject a clock or a sleep function so tests are fast and stable.

    0/3

    UI testing

    UI tests use the app like a real user. They are slow, so keep them few and focused.

    0/1
12. 12

    Performance and security

    0/6 learned

    Fast and safe apps are a sign of a senior engineer. Know how to measure speed and how to protect user data.

    App launch time

    Users notice a slow launch. You should know what happens before the first frame and how to make it faster.

    0/1

    Smooth scrolling

    A list should scroll at full frame rate. A dropped frame is called a hitch.

    0/2

    Profiling with Instruments

    Instruments shows where time and memory go. Always measure before you optimize.

    0/1

    Energy efficiency

    Apps that drain the battery get bad reviews. Know what uses the most energy and how to reduce it.

    0/1

    Keychain and data protection

    Secrets like tokens belong in the Keychain, not in UserDefaults. Data protection encrypts files when the device is locked.

    0/1

    ATS and certificate pinning

    App Transport Security forces HTTPS by default. Certificate pinning adds extra trust checks for your own servers.

    0/1
13. 13

    Tooling and release

    0/5 learned

    Shipping an app takes more than code. Know how builds are signed, set up and delivered.

    Code signing and provisioning

    iOS runs only signed apps. Signing problems are common, so interviewers like to ask how it works.

    0/1

    Build configurations and schemes

    Configurations and schemes let one project build for debug, staging and release. Each build can use different settings.

    0/1

    Swift Package Manager

    SPM manages dependencies and local modules. Most new projects use it instead of CocoaPods.

    0/2

    CI/CD

    CI builds and tests every change. CD sends builds to testers and the App Store automatically.

    0/1

    Versions and builds

    Each release has a version and a build number. Apps often compare versions to show a force-update screen.

    0/1
14. 14

    Algorithms in Swift

    0/7 learned

    Many companies still have a coding round. Learn the common patterns and write clean Swift.

    Arrays and hashing

    Many problems become easy with a dictionary or a set. This is the most common pattern in coding rounds.

    0/4

    Strings and sliding window

    Swift strings are not simple arrays of characters. Learn to work with them fast, and use a sliding window for substring problems.

    0/3

    Stacks and linked lists

    Swift has no built-in stack, queue or linked list. You must be able to build them quickly.

    0/3

    Binary search, intervals and matrices

    These patterns show up again and again. Learn the templates so you do not make off-by-one errors.

    0/4

    Trees and graphs

    Views, modules and files are all trees or graphs. iOS interviews often dress up graph problems in these terms.

    0/4

    Heaps and tries

    A heap gives you the smallest or largest item fast. A trie finds words by prefix. Swift has neither built in.

    0/3

    Recursion and dynamic programming

    Dynamic programming saves answers to small problems so you do not compute them again. Start with recursion, then add a cache.

    0/2
15. 15

    Mobile system design

    0/5 learned

    Senior interviews include a system design round. You design a full app feature and explain the trade-offs.

    A framework for the round

    A clear plan keeps you on track in a 45-minute round. Start with requirements, then design, then go deep.

    0/5

    Architecture, data and APIs

    Show the main parts of the app and how data moves between them. Then define the models and the server API.

    0/3

    Feeds, images and video

    Feeds and media apps are the most common design questions. They test caching, pagination and memory use.

    0/3

    Real-time and offline apps

    Chat, maps and notes apps must work with live data and a bad network. These are harder, senior-level designs.

    0/3

    Deep dives and observability

    The best answers go deep on one or two hard parts. They also explain how you will measure the app in production.

    0/3
16. 16

    Interview skills

    0/7 learned

    Knowing iOS is only half the job. You also need a plan, a good resume and clear answers in every round.

    How iOS interviews work

    Most companies use the same few rounds. Knowing them helps you plan your study time.

    0/3

    Resume

    Your resume gets you the first call. Show impact with numbers, not a list of tasks.

    0/1

    Coding rounds

    In a coding round, how you talk matters as much as the code. Explain your plan, write clean Swift and test it.

    0/3

    iOS knowledge rounds

    These rounds are rapid questions about Swift and iOS. Short, correct answers with an example work best.

    0/4

    UI coding and take-home tasks

    You may build a screen live or as a take-home project. Interviewers look at structure, states and polish.

    0/4

    Behavioral interviews

    Behavioral rounds check how you work with people. Prepare real stories before the interview.

    0/1

    Offers and negotiation

    The interview is not over at the offer. A short, polite negotiation often gets you more.

    0/1