无法将“Int”类型的值分配给“Int?.Type”类型 Swift 5

Question

I am trying to pass a value from one view controller to another of type Int .

Here is how I am invoking my sugue:

if questionNumber + 1 == quizBrain.quiz.count{
            self.performSegue(withIdentifier: "goToScore", sender: self)
        }

My prepare function is:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "goToScore" {
    let destinationVC = segue.destination as! ResultViewController
    destinationVC.finalScore = quizBrain.getScore()
        }
    }

Here is my destination view class:

import UIKit

class ResultViewController: UIViewController {

    var finalScore =  Int?

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

quizBrain.getScore() fetches a value of type Int . I am trying to pass this value and catch it in the other view in var finalScore .

The error I am getting is:

Cannot assign value of type 'Int' to type 'Int?.Type'

I am not sure what this particularly means, I am new to Swift and was unable to find something similar with a type Int?.Type . I am also running into a similar issue if I try passing a String in a different project.

Answer 1

Changing var finalScore = Int? to var finalScore:Int = 0 fixed it, Not sure if this is a Swift version issue. would be helpful if somebody could confirm why this worked.

Answer 2

An optional in Swift is a type that can hold either a value or no value. Optionals are written by appending a? to any type:

You should define an optional integer like:

var finalScore: Int? //now the value of finalScore can be nil or any integer value etc.

While using the option values, there are couple of ways:

if finalScore != nil {
    print(finalScore!)
}

or

guard let score = finalScore else {
    return
}

print(score)

or

print(finalScore ?? 0)

For more info, you can refer Apple Doc: https://developer.apple.com/documentation/swift/optional

Swift basics: https://docs.swift.org/swift-book/LanguageGuide/TheBasics.html#//apple_ref/doc/uid/TP40014097-CH5-XID_399