Run function every 24hrs swift 3 - swift3

Question

I got a list of quotes I am trying to update every 24hrs, based on the calender.
This is what I tried so far, but I am getting error Cannot convert value of type 'Date?' to expected argument type 'TimeInterval' (aka 'Double')
let numberOfQuotes = 3
let quotes = ["quote 1", "quote 2", "quote 3"]
override func viewDidLoad() {
super.viewDidLoad()
let timer = Timer.scheduledTimer(timeInterval: TimeInterval(30),
target: self, selector: #selector(self.updateQuote), userInfo: nil, repeats: true)
}
#objc func updateQuote() {
let lastUpdate = UserDefaults.standard.object(forKey: "lastUpdate") as? Date
if lastUpdate != nil {
let date1:Date = Date() // Same you did before with timeNow variable
let date2: Date = Date(timeIntervalSince1970: lastUpdate ) // **Getting error on this line**
let calender:Calendar = Calendar.current
let components: DateComponents = calender.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date1, to: date2)
if components.day! >= 1 {
UserDefaults.standard.set(Date(), forKey: "lastUpdate")
textView.text = "Hello there"
}
} else { //firstTime running
UserDefaults.standard.set(Date(), forKey: "lastUpdate")
textView.text = quotes[randomInt(min: 0,max: numberOfQuotes)]
}
}

Answer 1

lastUpdate is already a Date, the initializer Date(timeIntervalSince1970: is wrong and not needed anyway.
It's highly recommended to use optional bindings, and don't annotate types the compiler can infer.
if let lastUpdate = UserDefaults.standard.object(forKey: "lastUpdate") as? Date {
let date1 = Date()
let calender = Calendar.current
let components = calender.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date1, to: lastUpdate)
...

Answer 2

let date2: Date = lastUpdate!
UPDATE:
let components: DateComponents = calender.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date2, to: date1)