Xcode Swift 3: Timer and Segue View Controller Error - swift

Question

This code is in ViewController 1. goToMainUI is assigned to the segue connection ID between ViewController 1 and 2. Also, the storyboard ID for ViewController 2 is the same (goToMainUI). After the timer is finished, there is an error and the ViewControllers do not switch. Anyone know what the problem is? Thanks!
override func viewDidLoad() {
super.viewDidLoad()
let timer = Timer.scheduledTimerWithTimeInterval(8.0, target: self, selector: #selector(timeToMoveOn), userInfo: nil, repeats: false)
func timeToMoveOn() {
self.performSegue(withIdentifier: "goToMainUI", sender: self)
}

Answer 1

Try this code:
Note: Code tested in Swift 3.
Step 1: First set storyboard Segue Identifier
Step 2:
let emptyString = String() // Do nothing
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
Timer.scheduledTimer(timeInterval: 8.0, target: self, selector: #selector(timeToMoveOn), userInfo: nil, repeats: false)
}
func timeToMoveOn() {
self.performSegue(withIdentifier: "goToMainUI", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "goToMainUI") {
let dest = segue.destination as! viewTwo // viewTwo is your destination ViewController
dest.emptyString = emptyString
print("Segue Performed")
}
}
In your ViewTwo add this above viewDidLoad method.
var emptyString = String()