Add elements of custom array SwiftUI

Question

So I have a struct of Dice that has a few properties attached to it. I want to be able to add them all together so I have one clean value. Here is the struct:

struct Dice: Identifiable, Hashable {
    var id = UUID()
    var displayValue: String
    var initialValue: Int
    var endingValue: Int
            
    mutating func roll() {
        let randomInt = Int.random(in: initialValue..<endingValue)
        displayValue = "\(randomInt)"
        print("Initial: \(initialValue), EndingValue: \(endingValue), Display: \(displayValue)")
    }
}

They are stored within an array here: @State var viewArray: [Dice] = [] and then displayed in an ForEach here:

ForEach(0..<viewArray.count, id: \.self) { index in
    DiceView(dice: viewArray[index])
    .onTapGesture {
        self.viewArray.remove(at: index)
        withAnimation(.spring()) {
          
        }
    }
}

The thing I'm trying to do is grab the displayValue of each item in the viewArray and add them together. What is the best way of doing so? I'm assuming I need to create some sort of array based on the property of displayValue and then add that array together, but I haven't come across it yet.

So you want to create one string out of all the displayValue strings in the array, I would suggest map to get the property into an array and then joined to make one string from the array — Joakim Danielson
– Joakim Danielson, Commented Aug 8, 2020 at 18:20
Whoops! That's my fault, the displayValue should actually be an Int but essentially yes. How would I use map to grab the displayValue property directly? The examples I see are for grabbing just the direct values, but since my array is a custom type how do I map the custom values? — Frank Foster
– Frank Foster, Commented Aug 8, 2020 at 18:23
Not sure I follow, the main usage of map is to get a single property. Maybe you should read up on using map. — Joakim Danielson
– Joakim Danielson, Commented Aug 8, 2020 at 18:27

pawello2222 · Accepted Answer · 2020-08-08 21:29:37Z

1

If I understood you correctly you can try map + reduce.

Assuming the displayValue is of type Int (as you mentioned in the comments):

var viewArray: [Dice] = ...
let sum = viewArray.map(\.displayValue).reduce(0, +)

Assuming the displayValue is of type String you need to convert it to Int first:

var viewArray: [Dice] = ...
let sum = viewArray.map(\.displayValue).compactMap(Int.init).reduce(0, +)

edited Aug 8, 2020 at 21:29

answered Aug 8, 2020 at 18:41

pawello2222

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1 Comment

Frank Foster Over a year ago

Thank you! I think I ended up solving it but a little be more verbose:

let rollValues = viewArray.compactMap { Int($0.displayValue) }         let total = rollValues.reduce(0,+)         print("\(total)")

Same principle but different method I think. Thank you!

Frank Foster · Accepted Answer · 2020-08-08 19:01:12Z

0

Per @joakim I ended up solving this by creating:

 let rollValues = viewArray.compactMap { Int($0.displayValue) }
    let total = rollValues.reduce(0,+)
    print("\(total)")

and then assigning that to the variable I needed to display. Worked like a charm!

answered Aug 8, 2020 at 19:01

Frank Foster

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