closureExpressionBenchmark.swift

import QuartzCore
  

// make an Int array of random elements
let array = Array((1...2000).map { _ in Int(arc4random_uniform(2000)) } )

let loopCount = 100_000

// closure in a variable
let compareGreater: (Int, Int) -> Bool  = { $0 >  $1 }

// make sure the two methods produce the same result
assert(array.sorted(by: compareGreater) == array.sorted(by: { $0 >  $1 }), "Hey, You! The two are not the same!!!")

// pass closure as a variable
func useVariable() -> Double {
    let startTime = CACurrentMediaTime()
    for _ in 1...loopCount {
        // use a closure store in a variable
        _ = array.sorted(by: compareGreater)
    }
    return CACurrentMediaTime() - startTime
}


// pass closure as a literal
func useLiteral() -> Double {
    let startTime = CACurrentMediaTime()
    for _ in 1...loopCount {
        // use a closure literal
        _ = array.sorted(by: { $0 > $1 })
    }
    return CACurrentMediaTime() - startTime
}


print("Running benchmark...")

var variableTime = 0.0
var literalTime = 0.0

variableTime += useVariable()
literalTime += useLiteral()
literalTime += useLiteral()
variableTime += useVariable()

print("variableTime = \(variableTime)")
print("literalTime = \(literalTime)")
print("variableTime - literalTime = \(variableTime - literalTime)")