Convert input field string to Int in Swift

Question

So im very new to making APP ad Swift, im trying to do some very simple input in text fields, take the value, and use them as Int's for some calculations.

But something is not working correct with the 'var distance'

        var handicapTal:Int
        var MagicNumber:Int
        var handicap = inputHCP.text.toInt()
        var distance = inputDistance.text.toInt()

        if (handicap >= 0 && handicap <= 20)
        {
            handicapTal = 30
        }
        else if(handicap > 20 && handicap <= 40){
            handicapTal = 10
        }

        MagicNumber = distance - handicapTal

Its the last line of code that give an error. It says Fatal error: Cant unwrap Optional.None

Answer 1

distance, in your example, is an Int? otherwise known as an optional Int. .toInt() returns Int? since it is possible for the conversion from String to Int to fail. See the following example:

Welcome to Swift!  Type :help for assistance.
  1> let a = "12"
a: String = "12"
  2> let b = a.toInt()
b: Int? = 12
  3> let c = "Hello"
c: String = "Hello"
  4> let d = c.toInt()
d: Int? = nil
  5> if let e = a.toInt() { println("e = \(e)") }
e = 12
  6> if let f = c.toInt() { println("Huh?") }
  7>