Repeating at a certain time

Repeat every three seconds using Time.
I used it to create an app that functions like a clock.

	import UIKit

	class ViewController: UIViewController {

	var timer: Timer!

	override func viewDidLoad() {
	super.viewDidLoad()

	//3秒ごとに繰り返す、repeat every 3 seconds
	timer = Timer.scheduledTimer(timeInterval: 3.0, target: self, selector: #selector(self.update), userInfo: nil, repeats: true)
	timer.fire()
	}

	override func viewWillDisappear(_ animated: Bool) {
	super.viewWillDisappear(true)
	timer.invalidate()
	}

	@objc func update(tm: Timer) {
	//この関数を繰り返す、repeat this function
	print("Hello SwiSwiSwift")
	}
	}