colorswitchingcontentview.swift

import SwiftUI

struct ContentView: View {
    init(viewState: ViewState, rootHandler: @escaping (Message) -> ()) {
        self.viewState   = viewState
        self.rootHandler = rootHandler
        self.tabColor    = tabColors[0]
    }
    var body: some View {
        TabView {
            Dashboard(rootHandler).tabItem { Label("Dashboard", systemImage:"squareshape") }.onAppear(perform: { tabColor = tabColors[0] })
            Lights   (rootHandler).tabItem { Label("Lights",    systemImage:"lightbulb"  ) }.onAppear(perform: { tabColor = tabColors[1] })
            Rooms    (rootHandler).tabItem { Label("Rooms",     systemImage:"bed.double" ) }.onAppear(perform: { tabColor = tabColors[2] })
            Shop     (rootHandler).tabItem { Label("Shop",      systemImage:"cart"       ) }.onAppear(perform: { tabColor = tabColors[3] })
            Settings (rootHandler).tabItem { Label("Settings",  systemImage:"gear"       ) }.onAppear(perform: { tabColor = tabColors[4] })
        }
        .accentColor(tabColor ?? tabColors[0])
        .environmentObject(viewState)
    }
    @State private var animationCompletion: CGFloat = 0.0
    @State private var tabColor: Color!
    @ObservedObject
    private var viewState  : ViewState
    private let rootHandler: (Message) -> ()
}

fileprivate
let tabColors = [
    Color(hue:0.305, saturation:0.45, brightness:0.75),
    Color(hue:0.511, saturation:0.45, brightness:0.75),
    Color(hue:0.602, saturation:0.45, brightness:0.75),
    Color(hue:0.755, saturation:0.45, brightness:0.75),
    Color(hue:0.638, saturation:0.45, brightness:0.75),
    Color(hue:0.111, saturation:0.45, brightness:0.75),
]