2 Text boxes optional inserting in one or both - xcode

Question

I have two text fields to insert numbers, I am trying to find out how it could work out if the user is just inserting one value in one of the text fields or two. I tried to do it with if statements, but that does not work. Looks also like I have a mistake some where in the code I get the issue: fatal error: unexpectedly found nil while unwrapping an Optional value I would be happy for some help - as you can see I am a beginner in swift coding. Thanks so Far!
#IBOutlet var budgetShow: UILabel!
#IBOutlet var restShow: UILabel!
#IBOutlet var daysShow: UILabel!
#IBOutlet var dayssShow: UILabel!
#IBOutlet var inputDays: UITextField!
#IBOutlet var inputBudget: UITextField!
#IBAction func findResult(sender: AnyObject) {
var inputBudgetInt = inputBudget.text.toInt()
var inputDaysInt = inputDays.text.toInt()
var dailyRate = 85.50
if inputDays != nil {
var days = Double(inputBudgetInt!) / dailyRate
var daysCosts = dailyRate * days
var daysShow = Int(days)
var costsShow = Int(daysCosts)
dayssShow.text = "For \(costsShow) you can stay \(daysShow) Days."
}
if inputBudget != nil {
var budget = dailyRate / Double(inputBudgetInt!)
var budgetShow = Int(budget)
daysShow.text = "You need /(budgetShow)"
}
var daysBudget = Double(inputBudgetInt!) / Double(inputDaysInt!)
var show = daysBudget - dailyRate
var costs = Double(inputDaysInt!) * dailyRate
var rest = Double(inputBudgetInt!) - costs
var could = Double(inputBudgetInt!) / dailyRate
var couldShow = Int(could)
var restedShow = Int(rest)
var costShow = Int(costs)
var dayShow = Int(inputDaysInt!)
if show > 0 {
budgetShow.text = "For \(dayShow) Days you need \(costShow) €"
restShow.text = "Rest Budget after \(dayShow) Days is \(restedShow) €"
daysShow.text = "With your budget you could stay up to \(couldShow) days"
} else {
budgetShow.text = "Change your budget or days"
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}

Answer 1

One way to handle optionals safely is if let, like follows:
if let inputBudgetInt = inputBudgetInt {
// safely use it without need for "!" or "?"
var days = Double(inputBudgetInt) / dailyRate
}
This basically means "if this optional has a value, unwrap it and use it here".
I like to keep the name the same personally, you can use a different name if you want.
Another way is using "?", especially good for chaining. If you have a reference to a cell for example:
cell.textField?.text = "Foo"
If textField (optional) has no value, this line silently does nothing.
You should avoid "!" as much as possible as it can easily cause a crash. Only if you are 100% sure it has a value should you risk it. As a beginner I would stick to if let to make sure your optionals have values.