Peterson's algorithm for mutual exclusion

peterson.swift

import UIKit

var n: Int = 0;
var favoredProcess: String = "first"
var processOneWantsIn: Bool = false
var processTwoWantsIn: Bool = false

func processOne(task: () -> Void) {
    while n < 50 {
        processOneWantsIn = true
        favoredProcess = "second"
        while processTwoWantsIn && favoredProcess == "second" {
            print("Process one is waiting...")
        }
        task()
        processOneWantsIn = false
    }
}

func processTwo(task: () -> Void) {
    while n < 50 {
        processTwoWantsIn = true
        favoredProcess = "first"
        while processOneWantsIn && favoredProcess == "first" {
            print("Process two is waiting...")
        }
        task()
        processTwoWantsIn = false
    }
}

DispatchQueue.global(qos: .userInitiated).async {
    processOne {
        let date = NSDate().timeIntervalSince1970
        print("Process one is running at \(date)")
        n = n + 1
    }
}

DispatchQueue.global(qos: .userInitiated).async {
    processTwo {
        let date = NSDate().timeIntervalSince1970
        print("Process two is running at \(date)")
        n = n + 1
    }
}