Make an FPS counter in Swift

Source code

FPSCounter.swift

import Foundation

class FPSCounter {
    private var baseTime: Int!
    private var count: Int = 0
    private var fps: Float = 0

    func getFPS() -> Float {
        return fps
    }

    func tickStart() {
        baseTime = timeSince1970Millis()
    }

    func tick() {
        count = count + 1;
        let now = timeSince1970Millis()
        if (now - baseTime >= 1000) {
            fps = Float(count * 1000) / Float(now - baseTime)
            baseTime = now
            count = 0
        }
    }

    private func timeSince1970Millis() -> Int {
        return Int((Date().timeIntervalSince1970 * 1000.0).rounded())
    }
}

How to use

ViewController.swift

final class ViewController: UIViewController {

    private var fpsCounter = FPSCounter()

    override func viewDidLoad() {
        super.viewDidLoad()
        fpsCounter.tickStart()
    }

    private func hoge() {
        //Some processing

        fpsCounter.tick()
        print("fps: \(fpsCounter.getFPS())")
    }
}