Swift Topics to Master Before Applying to iOS Jobs
Breaking into the world of iOS development can be one of the most rewarding moves in tech. Whether you’re a recent university graduate, a career changer, or someone who’s fallen in love with Apple’s ecosystem, learning Swift is your ticket in.
But where should you focus your time before you hit “apply” on that junior iOS developer job?
In this blog post, we’ll walk you through the essential Swift topics that every aspiring iOS developer should feel confident with. Mastering these will not only make you job-ready — they’ll make you stand out
🚀 Why Swift Matters
Swift is Apple’s official programming language, used to build apps across iOS, macOS, watchOS, and tvOS. It’s fast, modern, safe, and expressive. Employers expect you to know Swift fluently — not just syntax, but how to use it to build maintainable, real-world systems.
Let’s look at the key areas of Swift you need to master before you apply.
1. Optionals & Optional Binding
Swift uses optionals to handle the absence of values safely. You must understand:
• What Optional means (? and !)
• How to unwrap safely with if let and guard let
• Implicitly unwrapped optionals
• Optional chaining
▶️ Employers want to see that you can avoid crashes and write safe, predictable code.
2. Control Flow (if, guard, switch, loops)
You must be confident using:
• if, else, and guard statements
• switch statements with fallthrough, where clauses
• for-in, while, and repeat-while loops
• Break and continue
3. Functions & Closures
Understand how to:
• Declare and call functions with multiple parameters
• Return values
• Use closures as callbacks (especially with async code like networking and animation)
• Use trailing closure syntax
Closures are everywhere in iOS development — from animations to completion handlers — so this is critical.
4. Structs vs. Classes
This is a fundamental Swift topic that shows you understand the language’s architecture. Learn:
• Value types (struct) vs reference types (class)
• Copying behavior vs reference sharing
• mutating keyword
• When to use which
Bonus: Know how enums fit in, especially with associated values and switch.
5. Properties
Understand:
• Stored vs computed properties
• Lazy properties
• willSet and didSet observers
• Static properties
These concepts appear often in real app logic — such as tracking user settings, responding to changes, and setting up state.
6. Protocols & Protocol-Oriented Programming
Swift is built on protocols, and iOS jobs will require you to:
• Understand protocol declarations
• Use protocol inheritance
• Apply protocol conformance
• Build flexible code using dependency inversion
Interviewers love to ask about how you can build scalable systems using protocols rather than inheritance.
7. Error Handling
Swift uses try, catch, and throws to manage errors. You should know:
• How to write functions that throw
• How to call throwing functions with try or try?
• When to use do-catch blocks
Don’t underestimate this one — a lot of iOS code (especially networking and file I/O) involves clean error handling.
8. Memory Management & ARC
Even at the junior level, you’ll be expected to understand:
• How Automatic Reference Counting (ARC) works
• The difference between strong, weak, and unowned references
• How to avoid retain cycles (especially in closures and delegates)
This is critical for building apps that don’t leak memory.
9. Basic Collections: Arrays, Sets, Dictionaries
Understand:
• How to declare, modify, and iterate over collections
• When to use a Set vs an Array
• How to work with keys and values in Dictionary
Expect to write code involving data transformation and filtering in any iOS job.
10. SwiftUI
Even though you should not focus on SwiftUI it would be a good idea to have some awareness of it and show that you have at least ran your code on an iOS Simulator.
Don't focus on learning SwiftUI (it will prove only to be a distraction), but understand some of its key points (such as being a reactive framework) before walking into the interview.
🎯 Final Tip: Practice in Xcode, Not Just Read
It’s not enough to read tutorials or watch videos. Employers want developers who’ve written real Swift code, using Xcode playgrounds or building small projects.
That’s why platforms like www.3DaysOfSwift.com are structured to get you practicing every single day.
💼 Ready to Apply?
Before you send that application, make sure you can:
• Write Swift code without copying and pasting
• Read and understand existing codebases
• Solve small problems without relying on Stack Overflow
• Build confidence through repetition and real tasks
Swift is powerful. And with focus and smart guidance, you can be too.
Learn it. Practice it. Apply with confidence.
Explore our learning path at www.3DaysOfSwift.com and make your application stand out.
Enrol below and get started with program 1.
Download a list of topics you will be required to know to pass an interview for an iOS Developer role. Download is below.
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Tips to Sky rocket Your Swift Career 🚀
Focus on learning the Swift language itself. Most team members start their learning journey by studying Xcode and building apps. It's a lot of information and plenty to get confused about. Most of your colleagues will have many gaps in knowledge that affect their every-day anxiety with completing tasks and having it reviewed by others. Instead, why not become the one of the reviewers? Our advice is to stand out in the tech industry and if you want to stand out I would suggest becoming very knowledgable about the language itself; Every single developer will be using it and they will all be competing over Architecture and not the best use of language features. Armed with an incredible understanding of the language you will have the confidence in knowing you can maintain any existing product on the market.
Gather "Career Things" like they were collectibles in a game. This easy-to-remember and rather broad term is a great bit of advice. Too many engineers let the months go by without really taking on board many exciting projects or doing anything that wows any one. This is a terrible idea in every way. Stand out. Be the best at something (like understanding the language). When you change positions and apply to a different company you will have an interview and they'll grill you with many questions. The main bits to know are these; Your CV gets you the interview. You display your worth in the interview.
Your CV gets you the interview: Your short 2 page bullet-pointed CV is simply a list of amazing things you did to improve the team, the social element, the code quality, the income, how you increased user retention, how you added a successful feature and improved the app. You must collect career things.
You display worth in the interview: In the interview you want to fill the hour with saying similar phrases non-stop to "I was able to tweak the values and affect the income of the product simply by reducing the friction of the onboarding and providing a more seamless and pleasant user experience for the user. We now have only a 14% drop compared to most companies that have around 30% typically." Notice how you use "we" when referring to your current company in interviews. To simplify the phrase just-used, "I helped my company move forward. I improved the product, which led to an increased user experience and ultimately more profits for the company. I am a team player and I will improve your company at every opportunity possible."
Become confident in Interviews. You are now a talented Swift engineer who understands the Swift language and has a list of successful results you can pull out of the bag and discuss and any interview. You are constantly and infinitely talking about specifics of the Swift language and how cool and useful it is. You are stacking up one example after another of how you affected the results of the team and the company. You are great at telling these stories. The world is your oyster and you can be confident in your abilities as well as your choices in life.
Move company every 2 years. Ask for a £10,000 increase. When you become bored at your current job because you know too much think about moving, upgrading your job title and doubling your annual salary.
Be driven and be proud that you help keep the world moving by maintaining the digital services we all love and are constantly glued to.
Not built with A.I. A human with decades of experience wrote this article. It's designed to help you and provide some real-life guidance to start a career in the tech industry with some solid success, lots of growth and being great at what you do.
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How to Learn Swift
Learn all topics in the Swift Study Guide, write tested systems in code alone & don't waste time building or learning UI (user interfaces). You can achieve all this at 3DaysOfSwift.com.
What Topics Do I need to Learn?
Foundational types, control flow, optionals, functions, closures, classes, structs, enums, value types, reference types, ARC (Automatic Reference Counting), extensions, protocols, concurrency, error handling and generics.
Below is the full list, available to download in markdown language.
Download
The recommended topics to study are those that each iOS Developer would be required or expected to know in order to pass an interview for a junior, mid-level or even a senior role.
Swift Study Guide
3DaysOfSwift.com | Online Swift Course
Beginner Topics
Topic 1: The Basics & Foundational Types
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/thebasics
Topic 2: Control Flow
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/controlflow
Topic 3: Optionals
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/optionalchaining
Topic 4: Functions
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/functions
Closures
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/closures
Topic 5: Classes
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/classesandstructures
Topic 6: Structs
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/classesandstructures
Topic 7: Enums
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/enumerations
Topic 8: Value Types
Reference Types
Topic 9: ARC (Automatic Reference Counting)
Mid-level Topics
Topic 10: Extensions
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/extensions
Topic 11: Protocols
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/protocols
Topic 12: Concurrency
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/concurrency
Topic 13: Error Handling
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/errorhandling
Topic 14: Generics
https://docs.swift.org/swift-book/documentation/the-swift-programming-language/generics
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How to Learn Swift
Learn all topics in the Swift Study Guide, write tested systems in code alone & don't waste time building or learning UI (user interfaces). You can achieve all this at 3DaysOfSwift.com.
Why not take our online course and learn Swift in a weekend?
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