susieyy

extension UIViewController {
    var previousViewController: UIViewController? {
        guard let navigationController = navigationController else { return nil }
        let count = navigationController.viewControllers.count
        return count < 2 ? nil : navigationController.viewControllers[count - 2]
    }
}

jrochkind

# test_for  == N / 5    -- approximate array average case?

{:benchmark_iterations=>10000, :class=>Array, :test_for=>5, :num_rewrites=>1, :col_size=>10, :num_reads=>10}
  0.140000   0.000000   0.140000 (  0.141915)

{:benchmark_iterations=>10000, :class=>Set, :test_for=>5, :num_rewrites=>1, :col_size=>10, :num_reads=>10}
  0.190000   0.010000   0.200000 (  0.198503)
----

{:benchmark_iterations=>10000, :class=>Array, :test_for=>50, :num_rewrites=>1, :col_size=>100, :num_reads=>10}

fredriccliver

import Foundation

extension String {
  var withoutPunctuations: String {
    return self.components(separatedBy: CharacterSet.punctuationCharacters).joined(separator: "")
  }
}

let originalStr:String = "hello, (Nice to- meet 한국 école %&$you all. 123 ! Давай العربية 😀"