Use iOS 16 environment variable while support older iOS?

Question

There are some new environment variable I need to use, for example

@Environment(\.requestReview) var requestReview // StoreKit

But my app needs to support older iOS. How do I "wrap" around this environment variable while not using iOS 16?

Answer 1

You can create your own extension for EnvironmentValues & in it do the check:

extension EnvironmentValues {
    var requestReviewOld: SomeType? {
        get {
            if #available(iOS 16.0, *) {
                self.requestReview
            }else {
                nil
            }
        }
        set {
            if #available(iOS 16.0, *) {
                self.requestReview = newValue
            }
        }
    }
}

Answer 2

I wish I could come up with a more idiomatic solution that would promote the usage of @Environment variables as the original API does, but declaring a new ViewModifier does the trick.

Start by declaring a new ViewModifier, followed by its extension, to make it available on View:

@available(iOS 16, *)
struct StoreReviewModifier: ViewModifier {
    @Binding var canRequestReview: Bool

    @Environment(\.requestReview) var requestReview

    func body(content: Content) -> some View {
        content
            .onChange(of: canRequestReview) { newValue in
                if newValue {
                    requestReview.callAsFunction()
                }
            }
    }
}

public extension View {
    @ViewBuilder func requestReview(_ canRequestReview: Binding<Bool>) -> some View {
        if #available(iOS 16, *) {
            modifier(StoreReviewModifier(canRequestReview: canRequestReview))
        } else {
            self
        }
    }
}

You can then use it as follows:

@State private var canRequestReview = false
    
var body: some View {
    ContentView()
        .requestReview($canRequestReview)
    }
}