EnumPicker.swift

import SwiftUI

struct EnumPicker<Enum>: View where Enum: CaseIterable & Hashable, Enum.AllCases: RandomAccessCollection {
    typealias Element = Enum.AllCases.Element
    
    private var enumType: Enum.Type
    @Binding private var selection: Element
    
    init(_ enumType: Enum.Type, selection: Binding<Element>) {
        self.enumType = enumType
        _selection = selection
    }
    
    var body: some View {
        Picker(String(describing: enumType), selection: $selection) {
            ForEach(Enum.allCases, id: \.self) { value in
                Text("\(value)")
                    .tag(value)
            }
        }
    }
}

extension Font.Leading: CaseIterable {
    public static var allCases: [Font.Leading] = [
        .loose,
        .standard,
        .tight,
    ]
}

extension Font.Design: CaseIterable {
    public static var allCases: [Font.Design] = [
        .default,
        .serif,
        .rounded,
        .monospaced,
    ]
}

#Preview(traits: .fixedLayout(width: 300, height: 300)) {
    struct Preview: View {
        @State var leading: Font.Leading = .standard
        @State var design: Font.Design = .default
        @State var dynamicTypeSize: DynamicTypeSize = .medium

        var body: some View {
            VStack {
                EnumPicker(Font.Leading.self, selection: $leading)
                EnumPicker(Font.Design.self, selection: $design)
                EnumPicker(DynamicTypeSize.self, selection: $dynamicTypeSize)
            }
            .dynamicTypeSize(dynamicTypeSize)
            .padding()
        }
    }
    return Preview()
}