How to set a custom random range in SwiftUI/Swift

Question

I need to create a custom range for random int in SwiftUI (or Swift).

Now I have two custom ints (minValue & maxValue, I will set them using TextField). So mainNum need to be ranged by them. I thought this would work, but no

@State var minValue: Int = 0
@State var maxValue: Int = 100
@State var mainNum: Int = Int.random(in: minValue...maxValue)

Answer 1

You can't use Int.random(in:) like that, because self isn't available. Instead, you should create the initial random number from the init where you have the range passed in - or you could create a default range in the initializer by changing it to this:

init(range: ClosedRange<Int> = 0 ... 100) {
    /* ... */
}

Here is an example of how you could do this, where the random number only is updated when you choose to (in this case, pressing a button).

struct ContentView: View {
    var body: some View {
        RandomNumberView(range: 0 ... 100)
    }
}

struct RandomNumberView: View {
    @State var range: ClosedRange<Int>
    @State var randomNumber: Int

    init(range: ClosedRange<Int>) {
        self.range = range
        randomNumber = .random(in: range)
    }

    var body: some View {
        List {
            Text("Random number: \(randomNumber)")

            Stepper(
                "Minimum: \(range.lowerBound)",
                value: Binding<Int>(
                    get: { range.lowerBound },
                    set: { range = $0 ... range.upperBound }
                ),
                in: 0 ... range.upperBound
            )

            Stepper(
                "Maximum: \(range.upperBound)",
                value: Binding<Int>(
                    get: { range.upperBound },
                    set: { range = range.lowerBound ... $0 }
                ),
                in: range.lowerBound ... 100
            )

            Button("Randomize") {
                randomNumber = .random(in: range)
            }
        }
    }
}

Result: