Updating time function every second in NSDate() - Swift - ios

Question

I have a function that gives me a time when the app is opened but I don't want it to be static I want it to be dynamic, updating every second. I thought of it being in a loop, but I don't know how to go about doing it. Doing a loop could work but if you have a better way of doing it please answer. Here is my function:
func timeNowString() -> NSString {
let date = NSDate()
var outputFormat = NSDateFormatter()
outputFormat.locale = NSLocale(localeIdentifier:"en_US")
outputFormat.dateFormat = "HH:mm:ss"
let timeString = outputFormat.stringFromDate(date)
return timeString;
}
Question: How do I make this function dynamic? So it goes and updates every second instead of it being a static label.
If you have any questions please comment down below.

Answer 1

Try this. You'll need to add a label and a button and hook them up to the textLabel and start IBAction. You can modify this to add hours (just minutes/seconds here) and add a timer.invalidate() where you need it.
import UIKit
class ViewController: UIViewController {
#IBOutlet var timeLabel: UILabel!
#IBAction func start(sender: AnyObject) {
var timer = NSTimer()
if !timer.valid {
let selector : Selector = "countTime"
timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target:self, selector: selector, userInfo: nil, repeats: true)
startTime = NSDate.timeIntervalSinceReferenceDate()
}
let timeNow = timeNowString() as String
for item in timeNow {
time = timeNow.componentsSeparatedByString(":")
}
}
var time = [String]()
var startTime = NSTimeInterval()
override func viewDidLoad() {
super.viewDidLoad()
}
func countTime() {
var currentTime = NSDate.timeIntervalSinceReferenceDate()
var elapsedTime: NSTimeInterval = currentTime - startTime
var adjustedTime = Int(elapsedTime) + 3600*time[0].toInt()! + 60*time[1].toInt()! + time[0].toInt()!
var hours = Int(Double(adjustedTime)/3600.0)
let minutes = Int(Double(adjustedTime - hours*3600)/60.0)
let seconds = adjustedTime - hours*3600 - minutes*60
let startHours = hours > 9 ? String(hours):"0" + String(hours)
let startMinutes = minutes > 9 ? String(minutes):"0" + String(minutes)
let startSeconds = seconds > 9 ? String(seconds):"0" + String(seconds)
timeLabel.text = "\(startHours):\(startMinutes):\(startSeconds)"
}
func timeNowString() -> NSString {
let date = NSDate()
var outputFormat = NSDateFormatter()
outputFormat.locale = NSLocale(localeIdentifier:"en_US")
outputFormat.dateFormat = "HH:mm:ss"
let timeString = outputFormat.stringFromDate(date)
return timeString;
}
}