Swift Playgrounds

A set of playgrounds that explains a Swift topic.

Details

These playgrounds cover a technical topic of Swift with examples. All explanations are in French.

Here's the list:

• @(non)escaping closures: What are the differences between @nonescaping and @escaping?

• @autoclosure: How to transform a function argument into a closure?

• @discardableResult: How to ignore the warning if the returned value of a function is not affected?

• ARC & Memory Leaks: How the Automatic Reference Couting (ARC) works – What is a memory leak and how do you fix it?

• ARC, Retain Cycle & Memory Leaks: How the Automatic Reference Couting (ARC) works – What is a memory leak and how do you fix it?

• Access Control: How can we restrict certain parts of our code, or on the contrary make it open?

• Array extensions & tricks: Functions of the standard library explained & some useful extensions.

• Custom Prefix, Postfix, Infix Operators: How do you create your own prefix / postfix / infix operators that act as functions behind the scenes?

• Defer: How to execute code just before the program leaves the scope of a function?

• Dependency Injection: What is injection dependence? - Why use dependency injection? - What are the different types of dependency injections?

• Enum extensions & tricks: enum with & without associated value, switch, if case let, guard case let, for case ... in, indirect enum.

• ExpressibleByStringLiteral: What is the purpose of the ExpressibleByStringLiteral protocol? – How do you conform to it?

• Grand Central Dispatch: asynchronous & synchronous execution, DispatchQueue, QOS, DispatchWorkItem, DispatchGroup, DispatchSemaphore and more.

• High Order Functions: filter, map, reduce, compactMap, flatMap & contains functions explained through examples.

• Keypath: What is a keypath? – Why you should use it? – How to create your own predicates?

• Lazy Property: What is a lazy property? – For which use case is it used? – What are the differences between a lazy property and a computed property?

• Literal Expression & Log function: #file, #filePath, #fileID, #line, #column, #function – How to create a function for logging?

• Opaque Return Type: What is a opaque return type? – What are the limitations of some? – How to compare two objects of an opaque return type? – What are the limits?

• Property Observers: What is a property observers? – How and when to use such a property?

• Protocols: How to declare and conform to a protocol? – How to create default implementations with protocol extension? – What is protocol inheritance?

• RawRepresentable: What is the purpose of the RawRepresentable protocol? – How do you conform to it?

• Static properties & functions: What are static properties and functions? – When to use them?

• Strings extensions & tricks: Tips on String thanks to custom extensions.

• Swift Concurrency: A file containing playgrounds for Swift Concurrency.

  • @globalActor, GlobalActor & @MainActor: What is a @globalActor? – How to create our own @globalActor thanks to the GlobalActor protocol? – What is @MainActor and when should it be used?

  • Actor: What is an actor? – What problems does it solve? – How and when to use it? – How to constrain protocols so that they can be conformed only by actors?

  • Async Let: How to create asynchronous constants with async let? – How to make parallel network calls?

  • Async await: How to create asynchronous functions with async await? – Why is it easier to read and understand asynchronous code? – How to adopt async await in an existing project?

  • AsyncSequence: What is the purpose of the AsyncSequence protocol? – How do you conform to it?

  • Sendable, @unchecked Sendable & @Sendable: What is the Sendable protocol? – What does it allow to do? – Why use @unchecked Sendable for classes? – Why and when to use @Sendable in closures?

  • Structured Concurrency: How to execute, cancel and monitor asynchronous operations?

• Swift Updates: A file containing playgrounds for Swift updates.

  • Swift 5.5
  • Swift 5.6

• Typealias: What is a typealias? – How to create a generic typealias?

• URLComponents + URLRequest: How to create robust get and post requests?

• Unit Tests: Which function should be used according to the desired test?

• init, init?, convenience init, requiered init: How to initialise a struct or a class with init, init?, convenience init or requiered init?

• private(set): What is private(set)? – When and why use it?

• try, throws & rethrows: What are the different ways to call a function that throws? – What problem does rethrows solve?

Resources

• Swift Documentation
• Improve your knowledge of Swift! by Vincent Pradeilles
• Hacking with Swift & What's new in Swift by Paul Hudson

Improvements

Some playgrounds need to be reworked to provide a better quality. However, if you notice errors or ambiguous passages, do not hesitate to open a PR.

Here's the list:

• ARC & Memory Leaks ∪ ARC, Retain Cycle & Memory Leaks
• init, init?, convenience init, requiered init: add a file for actor initialization.

Author

Lucas Abijmil, lucas.abijmil@gmail.com.

You can also reach me on Twitter.