Swift - Sum function error - ios

Question

I'm trying to make some view controllers that save a variable of a label every time and sum it to a total var. At the last view controller, show the result.
My code is:
FirstViewController
#IBAction func playSystemSoundV1(sender: UIButton) {
// Other code...
puntsLocal = 3
}
#IBAction func playSystemSoundRet(sender: UIButton) {
// Other code...
puntsLocal = 5
}
This code is similar for 5 controller. At the end of the controller I have a button to pass from one viewController to another. When I click I do the code above:
#IBAction func puntuacioAction(sender: UIButton) {
let puntuacion = Sum()
puntuacion.sumPoints(puntsLocal)
}
Sum Class
import Foundation
class Sum {
var points = 0
// Method to sum points from every question.
func sumPoints(num: Int) {
self.points += num
}
func getPoints() -> Int {
return points
}
}
The problem is that returns only the last number without do any kind of sum. What can I do? In other languages it's very easy to resolve but in Swift I cannot reach the answer. Help please!
Thanks.

Answer 1

You need to declare your variable outside the function:
let puntuacion = Sum()
#IBAction func puntuacioAction(sender: UIButton) {
puntuacion.sumPoints(puntsLocal)
}
Your original code created a new Sum everytime the function was called, explaining the behavior you are seeing. In Swift, variable declarations are bound to the scope they appear (e.g., inside a function, inside a class, etc).
If, besides that, you want to share this Sum object across many view controllers, this might help:
class Sum {
static let shared = Sum()
...
}
and use it like this:
#IBAction func puntuacioAction(sender: UIButton) {
Sum.shared.sumPoints(puntsLocal)
}
Of course, you should then delete the let puntuacion = Sum() line.