What Is 3DaysOf Swift?
- Jul 4, 2025
- 5 min read
What Is 3DaysOfSwift?
3DaysOfSwift is a free Swift revision platform designed to help iOS developers strengthen their understanding of the Swift programming language and prepare for technical interviews.
At first glance, that might sound similar to many other educational websites. The difference is that 3DaysOfSwift was not created to solve the problem of learning Swift from scratch. It was created to solve a different problem that many professional developers eventually encounter.
The problem is retention.
Most developers do not forget Swift because they were poor students. They forget Swift because modern software development is highly specialised. An engineer may spend six months focused on networking, another may spend a year building SwiftUI interfaces, and someone else may be concentrating on testing, accessibility, backend integration, or performance optimisation. During that time, language features such as ARC, generics, protocol composition, actor isolation, property wrappers, or value semantics may not appear often enough to remain fresh in memory.
When an interview suddenly appears on the calendar, many developers discover that concepts they understood perfectly well a year ago now feel surprisingly difficult to explain.
The knowledge has not disappeared, but it has become harder to access because it has not been revisited recently.
3DaysOfSwift was built specifically to help solve that problem.
Why Was 3DaysOfSwift Created?
The Swift community already provides exceptional learning resources.
Apple's official Swift language guide remains one of the most comprehensive programming language references available today. SwiftUI tutorials provide an excellent introduction to building applications, while WWDC sessions offer direct insight from the engineers building Apple's frameworks and tools.
Useful resources include:
The challenge facing many developers is not a shortage of educational material. If anything, the opposite is true. There are now thousands of hours of Swift content available online.
Courses, books, videos, blogs, newsletters, podcasts, and tutorials cover almost every topic imaginable.
What many developers lack is a practical and efficient way to revisit concepts they have already learned.
That observation became the foundation of the platform.
A Swift Revision Platform Rather Than A Traditional Course
Most educational platforms are built around progression.
Students begin at the start of a course, complete lessons in sequence, work through projects, and gradually advance towards more complex material. This approach works extremely well when somebody is learning Swift for the first time.
However, experienced developers often have different needs.
A developer preparing for an interview next week usually does not want to restart a forty hour course. They do not need to relearn variables, functions, and collections from the beginning. More often, they want to revisit specific topics, refresh their understanding, strengthen recall, and rebuild confidence in areas that may have become rusty over time.
3DaysOfSwift was designed around this style of learning.
The platform focuses on practical revision, experimentation, and helping developers reconnect with knowledge they already possess.
40 Free Downloadable Xcode Playgrounds
At the heart of the platform is a growing collection of downloadable Xcode playgrounds.
Today, 3DaysOfSwift provides 40 free downloadable Xcode playgrounds covering 29 Swift language features and concepts commonly encountered throughout professional iOS development and technical interviews.
Topics include:
Optionals
Protocols
Extensions
Closures
Generics
ARC
Property Wrappers
Concurrency
Actors
Opaque Types
Existential Types
Value Semantics
Reference Semantics
Protocol Extensions
Access Control
Error Handling
Rather than simply reading explanations, developers can open the playgrounds inside Xcode, run the examples, modify the code, test assumptions, and observe behaviour directly. This encourages active learning and often creates stronger retention than passive reading alone.
Inspired By The Swift Programming Language Book
One of the goals of the platform is to make the concepts discussed throughout Apple's Swift language guide more accessible through practical experimentation.
Many of the playgrounds are inspired by topics covered throughout The Swift Programming Language book and are designed to help developers interact directly with the concepts being discussed. Instead of reading about a feature and moving on, developers can immediately explore how that feature behaves within a working environment.
This approach helps bridge the gap between theory and practice while making revision significantly more engaging.
Built For Interview Preparation
Technical interviews remain one of the biggest reasons developers revisit Swift fundamentals.
Companies frequently ask candidates to discuss language concepts such as ARC, protocols, generics, concurrency, memory management, closures, architecture principles, and value semantics because these topics reveal how deeply a developer understands the language itself.
The challenge is that many of these concepts may not appear regularly throughout everyday development work. A developer can spend months building production features without needing to explain retain cycles or discuss actor isolation. During an interview, however, those same topics can become central to the conversation.
For this reason, interview preparation sits at the centre of much of the platform's content. The objective is not to help developers memorise answers. The objective is to strengthen understanding so that concepts can be discussed naturally and confidently when opportunities arise.
Everything Is Free
One of the most important decisions made during the development of 3DaysOfSwift was to make the entire playground collection freely available.
The platform originally explored several different directions, including more traditional educational models. Over time it became clear that the greatest value came from making revision resources as accessible as possible.
Today, every playground on the platform is free to download and use.
The goal is simple. If a developer wants to revisit concurrency, protocols, ARC, generics, closures, or any other Swift concept, they should be able to begin immediately without encountering unnecessary barriers.
Who Is 3DaysOfSwift For?
The platform is designed for several types of developers.
Graduates preparing for their first technical interview can use the playgrounds to strengthen their understanding of Swift fundamentals. Junior developers can revisit concepts encountered throughout their first few years in the industry. Experienced engineers can refresh topics that have not appeared recently in day to day work. Even senior developers often find value in revisiting language features before interviews or career transitions.
While the platform can certainly help beginners, its greatest strength is helping developers retain and reinforce knowledge they have already acquired.
Final Thoughts
3DaysOfSwift exists because learning Swift and remembering Swift are different challenges.
The Swift community already provides exceptional resources for learning the language.
What many developers need later in their careers is an efficient way to revisit important concepts, strengthen recall, and maintain confidence in their technical abilities.
Through 40 free downloadable Xcode playgrounds covering 29 Swift language features and concepts, 3DaysOfSwift aims to provide exactly that. Whether you are preparing for an interview, returning to Swift after a break, or simply looking to keep your skills sharp, the platform was created to help you strengthen the knowledge you have already worked hard to acquire.
You can explore the complete collection here:
Good luck.
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