Playground demoed during threads in swift meetup

GCDPlayground.swift

//: Playground - noun: a place where people can play

import Cocoa
import PlaygroundSupport
PlaygroundPage.current.needsIndefiniteExecution = true


//-----------------------------------
// Source: https://www.appcoda.com/grand-central-dispatch/
func queuesWithQosExample() {
    let queue1 = DispatchQueue(label: "com.example.myqueue", qos: .userInteractive)
    let queue2 = DispatchQueue(label: "com.example.myqueue2", qos: .utility)
    
    queue1.async {
        for i in 0..<10 {
            print("🔴", i)
        }
    }
    
    queue2.async {
        for i in 100..<110 {
            print("🔵", i)
        }
    }
}

//queuesWithQosExample()

//-----------------------------------
// Source: https://www.appcoda.com/grand-central-dispatch/
func concurrentQueuesExample() {
    
    let queue = DispatchQueue(label: "com.example.myqueue", qos: .utility, attributes: .concurrent)
    
    queue.async {
        for i in 0..<10 {
            print("🔴", i)
        }
    }
    
    queue.async {
        for i in 100..<110 {
            print("🔵", i)
        }
    }
    
    queue.async {
        for i in 1000..<1010 {
            print("⚫️", i)
        }
    }
}

//concurrentQueuesExample()

//-----------------------------------
// Source: Paul Hudson. “Hacking with macOS.”
func runMultiprocessing(useGCD: Bool) {
    func fibonacci(of num: Int) -> Int {
        if num < 2 {
            return num
        } else {
            return fibonacci(of: num - 1) + fibonacci(of: num - 2)
        }
    }
    
    var array = Array(0 ..< 24)
    let start = CFAbsoluteTimeGetCurrent()
    
    if useGCD {
        DispatchQueue.concurrentPerform(iterations: array.count) {
            array[$0] = fibonacci(of: $0)
        }
    } else {
        for i in 0 ..< array.count {
            array[i] = fibonacci(of: array[i])
        }
    }
    
    let end = CFAbsoluteTimeGetCurrent() - start
    print("Took \(end) seconds")
}

//runMultiprocessing(useGCD: true)
//runMultiprocessing(useGCD: false)

//-----------------------------------

sleep(3)
PlaygroundPage.current.finishExecution()