CODEWITHSUNDEEP
iosarraysswift
NewBeginnings
NewBeginnings

Reputation: 347

Immutable value of type '[String]' only has mutating member

Getting the error of Immutable value of type '[String]' only has mutating member in my swift project and researched some answers and none seem to fix the problem in my context. Take A Look: import UIKit

class PassionViewController: UIViewController {

   var factIndex = 0
   var counter = 1


    @IBOutlet var QuoteImage: UIImageView!

    @IBOutlet weak var funFactLabel: UILabel!

    let factBook = FactBook()
    let Liked = Favourite()
    override func viewDidLoad() {
        super.viewDidLoad()



        funFactLabel.text = factBook.factsArray[factIndex]
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }




    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

    @IBAction func showFunFact() {
        factIndex++
        if (factIndex >= factBook.factsArray.count) {
            self.factIndex = 0
        }
        funFactLabel.text = factBook.factsArray[factIndex]

        if counter == 36 {

            counter = 1

        } else {

          self.counter++

        }

        QuoteImage.image = UIImage(named: "frame\(counter).jpg")

    }
    @IBAction func goBack() {
        factIndex--
        var number = factBook.factsArray.count-1
        if (factIndex < 0){
            self.factIndex = number


        }
        funFactLabel.text = factBook.factsArray[factIndex]
        if counter == 1 {

            counter = 36

        } else {

            self.counter--

        }

        QuoteImage.image = UIImage(named: "frame\(counter).jpg")

    }
    @IBAction func Like() {


    let currentQuote = factBook.factsArray[factIndex]
           Liked.favouriteArray.append(currentQuote)
        }
    }

The let currentQuote = factBook.factsArray[factIndex], factBook.factsArray is retrieved from another view controller which is a array collection. Liked.favouriteArray.append(currentQuote) is to store this element into favouriteArray which is from a struct called Favourite:

import Foundation



struct Favourite {

    var favouriteArray:[String] = []








}

However, the line Liked.favouriteArray.append(currentQuote) is generating the error: Immutable value of type '[String]' only has mutating member. How can I resolve this error?

Upvotes: 2

Views: 182

Answers (1)

Rob Napier
Rob Napier

Reputation: 299265

It's unclear because you didn't provide the Favourite type, but I assume it's either a struct, or it's a class that includes factsArray as a let variable. In either case, you're trying to modify a let variable, which is not allowed (mutating an immutable value). Either liked or factsArray must be var. (If Favourite is a struct, then liked must be var in either case.)

Note that Swift functions, methods, properties, and variables should start with a lowercase letter. Leading uppercase letters denote types.

Upvotes: 2

Related Questions