A simple program to benchmark performance of removeAll() method for Set

nativeRemoveAllPerformance.swift

import Foundation

var before = NSDate()
var after = NSDate()
var duration: NSTimeInterval = 0
var a = Set(Array(1..<9999).sort {_, _ in arc4random() % 2 == 0})

(1...10000).forEach { _ in
    var b = a
    before = NSDate()
    b.removeAll(keepCapacity: true)
    after = NSDate()

    duration += after.timeIntervalSinceDate(before)
}

print(duration)