Track how long a function takes to run and report progress

ProgressReporter.swift

//Prints:
//
//Get filenames
//Progress 100000/2000000
//Progress 200000/2000000
//Progress 300000/2000000
//...
//Progress 2000000/2000000
//Completed
//Time taken to get filenames: 100 secs

//Use it like this:

func getFileNames(someInput: [String]) {
  let progress = ProgressReporter(name: "get filenames", total: someInput.count)
  var results = [String]()
  for e in results {
    someAsyncOperation(e) {
      progress.update(current: results.count) {
        //do something with results
      }
    }
  }
}

import Foundation

class ProgressReporter {
  let startTime = Date()
  var name: String
  var total: Int
  var step: Int

  init(name: String, total: Int = -1, step: Int = 100000) {
    self.name = name
    self.total = total
    self.step = step
    print("\(name.firstUppercased)...")
  }

  func update(current: Int, completion: (()->())? = nil) {
    if current % step == 0 {
      print("Progress \(current)/\(total)")
    }
    if current == total {
      completed()
      completion?()
    }
  }

  func completed() {
    print("Completed")
    print("Time taken to \(name): \(Date().timeIntervalSince(startTime)) secs")
  }
}

extension String {
  var firstUppercased: String {
    guard let first = first else { return "" }
    return String(first).uppercased() + dropFirst()
  }
}