Functional Reactive Programming

• Interactive Newton's Cradle - Apple's interactive playground of a Newton's Cradle where collisions and gravity are applyed with UIKit dynamics. 🌟 (updated to Swift 3 by @p-sun)
• Apple's Balloons Playground - The balloons playground showed at WWDC14. ⏳
• Apple's Crustacean Playground - Protocol-Oriented Programming with Value Types. ⏳
• Apple's Swift Standard Library Playground - experiment with Swift standard library types and high-level concepts using visualizations and practical examples. ⏳
• Apple's Mandelbrot Playground - A playground with the mandelbrot fractal (updated to Swift 3 by @palmerc, @kemalenver).

Algorithms and Data Structures

• Swift Algorithm Club - Algorithms and data structures in Swift with explanations. 🌟
• Swift Algorithm Club - Algorithms and data structures in Swift with explanations. 🌟
• Swift Algorithm Club - Algorithms and data structures in Swift with explanations. 🌟
• Animated Sorting Algorithms - Swift 4 playgrounds to view and manipulate sorting algorithms.🍁
• Expressions - Arithmetic and logical expressions elegantly modeled and visualized using protocol-oriented binary trees.🍁
• Sorting Experiments - Alluring experiments with sorting algorithms in Swift, sort of.
• Visual Binary Trees - Effortless visualization of arbitrary Binary Trees, along with their pluggable traversal implementations. 🌟
• Julia Fractal Playground - A Swift playground that generates beautiful Julia set fractal images.
• A Star - Protocol oriented A* pathfinding algorithm implementation in Swift 4.🍁
• DataStructures Playground - Data Structures and Algorithms in Swift. ⏳
• Swiftography - Standard cryptographic algorithms in a Swift Playground. ⏳
• Algorithms Playground - Various algorithm implementation in Swift. ⏳
• The Jelly Bean Problem - The Jelly Bean problem from Wait But Why. ⏳
• Euclidean Strings - A playground leveraging ReSwift to generate Euclidean Strings. ⏳
• Swift Algorithm Club - Algorithms and data structures in Swift with explanations. 🌟

Functional Reactive Programming

• Functional Debug View - Playground to visualize functional programming with graphical sequences. 🍁 🌟
• OOP with Functions in Swift - Object-Oriented Programming in Functional Programming in Swift. 🍁
• Logician - Logic programming in Swift. 🌟
• Function Composition in Swift - Exploration of function composition in Swift. 🌟
• Swift Adventures in Monad Land - Learn about monads.
• Functional Design Patterns - A few functional programming concept and patterns.
• Learn about transducers - A little tutorial that explains transducers. ⏳
• Functors in Swift - A playground to introduce Functors in Swift, and their practical usage. ⏳
• Swift Functors, Applicatives, and Monads in Pictures - Companion to the article: Swift Functors, Applicatves, and Monads in Pictures. ⏳

Languages

• Introduction to Compilers - Great introduction to the inner workings of compilers. 🍁🌟
• Pascal Interpreter - Simple Swift interpreter for the Pascal language inspired by the Let’s Build A Simple Interpreter article series. 🍁
• Write your own language: Mu - A playground explaining how to create a tiny programming language named Mu. 🌟
• Register VM - A register-based VM in a Swift playground. 🌟 ⏳
• Turtle Playground - A playground with Logo-like commands. 🌟 ⏳
• Swift Brainfuck - Brainfuck interpreter written in Swift using Playground. ⏳
• ASM Swift - A playground for learning Assembly language through Swift. 🌟
• Let's build a compiler in Swift - Let's Build a Compiler by Jack Crenshaw translated to Swift Playgrounds. 🌟

Machine Learning

• Emoji Intelligence - Neural Network built in Apple Playground using Swift. 🌟

Machine Learning

• WWDC16 Logo Playground - Drawing the WWDC16 logo in a playground. ⏳
• UIStackView Playground - Interesting examples of use of UIStackViews.🌟
• Bezier Path Playgrounds - Some playgrounds to better understand UIBezierPaths.
• UIKit playground - Playgrounds to experiment interactively with UIKit views.
• UIDynamic Playground - Multiple Playgrounds using almost every behaviour of UIDynamic.
• WWDC16 Typography - Draw a logo or any text with the WWDC16 ASCII texture.
• Animated GIF Playground - Swift playground for generating animated GIFs.
• RPClarity - Shows a technique for blurring an image behind the characters behind one or more UILabels. ⏳
• Swift Clock - An animated clock in a swift playground. ⏳
• WatchKit Asset Playground - A swift playground for creating awesome animations for your WatchKit Apps. ⏳
• Swift 2.0 Protocol Extension Example - Showing how to use Swift2 protocol extensions to render errors in UIViews and UIViewControllers without subclassing or creating classes. ⏳
• Tinting - A small playground to demonstrate image tinting in UIKit. ⏳
• Ray tracing Playground - A playground and a series of articles on ray tracing, see also part [2](https://github.com/mhorga/Raytracing2), [3](https://github.com/mhorga/Raytracing3), [4](https://github.com/mhorga/Raytracing4), [5](https://github.com/mhorga/Raytracing5) 🌟 ⏳

Core Image

• Interpolation Playground - Playground demonstrating lerp, smooth step, Catcall-Rom and others! ⏳
• CoreImage for Swift Playgrounds - Growing collection of CoreImage playgrounds from the upcoming book "CoreImage For Swift". 🌟 ⏳
• Image Processor - Implementing different image filter algorithms. ⏳

Metal

• Metalbrot - Interactive playground that draws the Mandelbrot fractal with Metal. 🌟
• METAL Playground - Apple Metal framework playground. 🌟 ⏳

Animations

• Core Animation Swift Playgrounds - A set of interesting Core Animation playgounds.
• UIViewPropertyAnimator Playground - Playground demonstrating UIViewPropertyAnimator.
• WWDC Crowd Simulator 2017 - A SpriteKit experiment to simulate the WWDC2017 logo crowd.
• Duet-Inspired Trail Effect - How to get a Duet style trailing effect in SpriteKit.
• Additive Animations - Experiment with multiple additive animations in Core Animation. ⏳
• Core Animation Playground - Companion to Apple's Core Animation Programming Guide. ⏳
• Core Animation Timing - Playground demonstrating effects of CAMediaTiming properties. 🍁

SpriteKit

• SceneKit ARKit Demo - The Xcode 9 ARKit SpriteKit demo as a playground.🍁
• SpriteKit Swift 3 - Playground for exploring Sprite Kit.
• SpriteKit Collisions - Demonstrates how to perform physics collision detection using Swift and SpriteKit. ⏳
• SceneKit Examples - Experiment with SceneKit and Swift. ⏳
• Astronomy - A 3D earth model written in swift playground using SceneKit.

SpriteKit

• Numerical Algorithms - Numerical argorithms playground from Ray Wenderlich. ⏳
• Abstract Algebra - Abstract algebra concepts implemented in Swift.
• Lindenmayer Systems - A Swift playground exploring Lindemayer systems.
• Swift Natural Numbers - A playground for implementing the natural numbers and more concepts in number theory.
• Polydoxical - Interactive playground to experiment with roulettes and polygons.
• Abstract Algebra - Abstract algebra concepts implemented in Swift.
• Swift Accelerate - Using the Accelerate framework and Swift for Linear Algebra. ⏳
• Guilloche Pattern Playground Book - Learn more about this pattern you see every day, but probably never knew it was really carefully designed. 🍁
• Swifty Mathematics - A collection of swift playground about mathematics. ⏳

SpriteKit

• AIToolbox - A set of playgrounds showing machine learning algorithms, all implemented with pieces of the AIToolbox framework code.
• AudioKit Playgrounds - 130+ Audio synthesis, processing, playback, and analysis playgrounds with AudioKit.
• AudioKit Playgrounds - 130+ Audio synthesis, processing, playback, and analysis playgrounds with AudioKit.
• Cognitive Service APIs - Get started with the Microsoft Cognitive Services APIs.
• Rx Playground - A playground with RxSwift examples.

SpriteKit

• ManuelCarlos's Playgrouds - Various playgrounds.
• Public Extensions - A set of useful extensions from [@PublicExtension](https://twitter.com/publicextension). 🌟
• Swift fun playgrounds - A few playgrounds to showcase Swift peculiar features. ⏳
• Parks And Recreation - Great collection of interesting playgrounds, for fun and for profit. 🍁🌟
• URaimo's Playgrounds - My playgrounds, various topics. 🍁
• Mgrebenets's Playgrounds - Various playgrounds.c 🌟
• Cocoa With Love Playgrounds - Playground versions of select articles from Cocoa with Love. 🌟
• Sketchytech's Playgrounds - Various Playgrounds. 🌟 ⏳
• Swift fun playgrounds - A few playgrounds to showcase Swift peculiar features. ⏳
• BradLarson's Playgrounds - Various playgrounds. ⏳
• Dmikusa's Playgrounds - Playgrounds that show basic Swift, JSON parsing, sending HTTP requests and basic file IO. ⏳
• Uberbruns's Playgrounds - Various playgrounds. ⏳
• Cananito's Playgrounds - Various playgrounds. ⏳

SpriteKit

• SwiftChain - Simple Cryptocurrency in a Swift Playground.
• Rubik's Cube - Implementing basic model and behavior of Rubic's Cube in Swift. 🍁
• Icon Creator - Create app icons on Swift playground.
• 2048 Playground - The 2048 game implemented with a playground.
• SwiftShell - Bash shell in a playground.
• LaunchPad Playground - A playground that simulates a real LaunchPad for making music.
• Super Maze - A programmatic maze generator and solver.
• Tic Tac Toe - Tic tac toe in a playground.
• Pixel Art Maker - A playground where you can make pixel art.
• SwiftCoin - A simplistic blockchain & cryptocurrency in a playground.
• SentimentlySwift - Sentiment analysis in Swift.
• Game Boards - Chess, checkers, tic-tac-toe, sudoku and many others in playground. 🌟 ⏳
• SwiftFiles - Save, Load and Delete files easily from within a Swift playground. ⏳
• Earth photos - A slideshow of Earth photos taken by DSCOVR/EPIC. 🌟 ⏳
• StarWars Seals - Emblems from Star Wars in Swift playgrounds via CoreGraphics and UIViews. ⏳

• A Swift Introduction to Core Data - Learn Core Data experimenting directly in this playground. 🌟
• TDDSwiftPlayground - Demonstration of using Swift Playgrounds in Test Driven Development with XCTest.
• Concurrency on iOS - Concurrency and Parallelism in iOS.
• Modern Core Data - An introduction to Core Data.
• Swift DSL Example - Implementation of a DSL in Swift.
• Katan - A micro web server that replies "Hello world!" to every request, an example of how to use sockets in Swift.
• Swift Regular Expressions - A playground to learn regular expressions with Swift.
• Network Stack - Clean & simple Swift networking stack playground.
• Swiftly Typed Resources - A playground showing how Swift makes Strings, Colors, Fonts, Images, etc easier to deal with. ⏳
• Swift Date Tutorial - Learn everythig about NSDate. ⏳
• Swift And C - Examples about using C with Swift. ⏳
• Swift Memory Management - How to avoid retain cycles, from [this post](http://detho.re/2016/01/21/writing-memory-efficient-swift-code/). ⏳
• Swift KVO Closures - Swift KVO playground. ⏳

Design Patterns

• Design Patterns Playground - Learning GoF's Design Patterns in Swift 3.
• iOS Design Patterns - Sample projects for MVC, MVP, MVVM, and VIPER.
• Design Patterns in Swift - Design patterns in Swift 3.
• GOF Swift - Learn all 23 Gang of Four patterns using Swift.
• The Principles of OOD in Swift 4 - The Principles of OOD based on Uncle Bob articles.🍁

Protocol Oriented Programming

• Swift Diagram Playgrounds - Adaptation of the Protocol-Oriented Programming in Swift talk from WWDC 2015.
• Swift Protocol Extensions - A playground to explore Protocol Extensions. ⏳
• Battleship Example - An example of how to use Protocol Oriented Programming with the battleship game. ⏳

Functional Reactive Programming

• ReactiveCocoa Playground - The easiest way to get a taste of ReactiveCocoa. ⏳
• Swift Reactive Playground - Companion to the article: ReactiveCocoa made Simple With Swift. ⏳

Functional Reactive Programming

• XCTest Playground - Better looking tests for playgrounds.
• Interactive Playground - Exploring interactivity in Playgrounds.
• Mondrian - Make iOS app mockups in Swift 2.x playgrounds. ⏳

Functional Reactive Programming

• iPad Swift Playgrounds - The sample playgroundbooks converted to playgrounds.

SpriteKit

• Bach Playground - A Simple Swift Playground that plays a brief piece by Bach with AVAudioEngine and AVMIDIPlayer.
• PlayerNode Playground - Playground using AVAudioEngine with a playernode and effects to play an audio file. 🌟
• Miles - A Swift Playground that creates jazz improvisations in any key using AudioToolbox and AVFoundation.
• Rhythm Snap - A Swift Playground using Vision and AVFoundation to help you practice rhythm in a fun way.🍁