EnvironmentObject to Binding

Question

magnuskahr OP

Created Jun ’20

Replies 1

Boosts 0

Views 4.2k

Participants 2

Hello,

how do I convert an EnvironmentObject to a Binding?
In my GameView have have:

GameView.swift

Code Block struct GameView: View {
	@EnvironmentObject private var game: ObserveableGame
	var body: some View {
		...
		.sheet(isPresented: $addingPoints) {
			 AddPointsView(game: $game)
		}
	}
}

and my AddPointsView:

Code Block struct AddPointsView: View {
	@Binding var game: ObserveableGame
	var body: some View {
		...
	}
}

But in the GameView.swift I get an error on the (translated) line 6:

Cannot convert value of type 'EnvironmentObject<ObserveableGame>.Wrapper' to expected argument type 'Binding<ObserveableGame>'

How do I make a binding to an EnviromentObject?

Answered by Developer Tools Engineer in 617513022

You don’t. An @Binding is mutable (you could set AddPointsView.game to a different value) but @EnvironmentObject is not mutable (you can set the properties of GameView.game, but you can’t replace the entire GameView.game object with a different one). So you can get bindings to GameView.game’s properties through GameView.$game, but you can’t get a binding to GameView.game itself.

Consider separating ObservableGame into a struct which contains your game data and a class which manages a property of the struct’s type. Then you’ll be able to take a binding of your game data struct and pass it to the child. Alternatively, consider using @ObservedObject on AddPointsView.game, rather than Binding.

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Answer 1

Developer Tools Engineer OP

Apple

Jun ’20

Accepted Answer

You don’t. An @Binding is mutable (you could set AddPointsView.game to a different value) but @EnvironmentObject is not mutable (you can set the properties of GameView.game, but you can’t replace the entire GameView.game object with a different one). So you can get bindings to GameView.game’s properties through GameView.$game, but you can’t get a binding to GameView.game itself.

Consider separating ObservableGame into a struct which contains your game data and a class which manages a property of the struct’s type. Then you’ll be able to take a binding of your game data struct and pass it to the child. Alternatively, consider using @ObservedObject on AddPointsView.game, rather than Binding.

1