Swiftui: @environmentObject - Cannot use instance member within property initializer; property initializers run before 'self' is available

Question

I try to pass data from an @environmentObject to a @State object in the TopLevel

struct ContentView: View {

    @EnvironmentObject var countRecognizer: themeCounter
    @State var theme: themeModel = themeData[countRecognizer.themeCount]

    @State var hideBar = true

    var body: some View {
        ZStack {
            videoCard(theme: theme)
                .statusBar(hidden: true)

            Text("\(self.countRecognizer.themeCount)")

            if hideBar == true {

            }
        }

But I am getting this error: "Cannot use instance member within property initializer; property initializers run before 'self' is available"

the themeData Array should get the Int from the environment Object.

How can I fix this problem?

There is no `themeData` declaration in provided code - would you show how you pass it in? Is it global variable? — Asperi, Apr 20 '20 at 10:05
themeData is from an Array following the Class, called themeModel: — Ian, Apr 20 '20 at 10:15
import SwiftUI let themeData: [themeModel] = [ themeModel(titleL1: "", titleL2: "", subHead: ""), — Ian, Apr 20 '20 at 10:15

score 1 · Answer 1 · answered Apr 20 '20 at 10:02

1

do your

theme: themeModel = themeData[countRecognizer.themeCount]

in

.onAppear(...)

answered Apr 20 '20 at 10:02

workingdog

3,125
1
5
13

1

this won't fix the issue, as `themeModel` is non optional. It will work if you make `var theme: themeModel?`, but at that point you have to make a view that supports having `nil` as a `theme` – Tiziano Coroneo Apr 20 '20 at 10:19

score 0 · Answer 2 · answered Apr 20 '20 at 10:17

0

You cannot use countRecognizer directly from the initial value of another property, and there is no easy fix.

I suggest you to look into refactoring your @State var theme property into a @Published var theme inside the themeCounter ObservableObject. Apple tutorials will help you: https://developer.apple.com/tutorials/swiftui/tutorials

As an aside: DON'T NAME TYPES WITH A LOWERCASE.

themeModel should be ThemeModel
themeCounter should be ThemeCounter
videoCard should be VideoCard

answered Apr 20 '20 at 10:17

Tiziano Coroneo

601
4
16

Thanks, Mate. My main issue is to control the ThemeData input with a gesture. The environmentobject was an approach. If I put "var theme" inside the ThemeCounter as a published, how can I pass it to videoCard(theme: theme)? – Ian Apr 20 '20 at 21:05
`themeCounter.theme` ? – Tiziano Coroneo Apr 22 '20 at 14:51

Swiftui: @environmentObject - Cannot use instance member within property initializer; property initializers run before 'self' is available

2 Answers2