Class to Struct causing reassigning of variable not to work

Question

sorry to bother with something that is probably pretty easy.

Here is my code now the only difference is instead of 'struct' it was a 'class'. Now it's causing the changeAmount function to no longer work. I have tried declaring it as 'let' etc, but it shows other errors. If anyone has a fix that would be great.

struct Product {
    var ID : String = ""
    var name : String = ""
    var type : String = ""
    var price : Double = 0.00
    var image : String = ""
    var amount : Int = 1
    var imageURL : String = ""
    var thumbnailURL : String = ""
    var description : String = ""

    init(id:String, name:String, description:String, type:String, price:Double, image:String, imageURL:String, thumbnailURL:String, amount:Int = 1) {
        self.ID = id
        self.name = name
        self.description = description
        self.type = type
        self.price = price
        self.image = image
        self.imageURL = imageURL
        self.thumbnailURL = thumbnailURL
        self.amount = amount
    }

    func changeAmount(a:Int){ self.amount = a }
}

(Actually the same question was asked, answered, and closed as a duplicate just 30 minutes ago :) — Martin R, Apr 18 '15 at 20:00
Sorry! I wasn't sure how exactly to phase the question.! Mutating tag seems to have worked, thanks as always guys! — Austin Sweat, Apr 18 '15 at 22:09
Can anyone explain why `mutating` I'd like to learn why exactly. — Austin Sweat, Apr 18 '15 at 22:10

score 1 · Accepted Answer · answered Apr 18 '15 at 19:58

1

If a function will change the contents of a struct, you need to declare it as mutating:

mutating func changeAmount(a:Int){
    self.amount = a
}

answered Apr 18 '15 at 19:58

Aaron Brager

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Thanks! Can you explain why `mutating`? – Austin Sweat Apr 18 '15 at 22:08

Class to Struct causing reassigning of variable not to work

1 Answers1