Widget showsWidgetContainerBackground fallback

Check your runtime warnings in Xcode. I have seen it tell me the SwiftUI environment variables can only be used in a view.

In my widgets I already have a wrapper view to handle a lot of common things & bootstrap. I have a view "WidgetSetStuff" that sets global variables -- or it could adjust a class object passed in.

struct WidgetEntryView : View
{
    ...
    @Environment(\.widgetFamily) var widgetFamily
    @Environment(\.showsWidgetContainerBackground) var showsWidgetContainerBackground

    var body: some View
    {
        ...
                WidgetSetStuff(
                    family: widgetFamily,
                    noMargins: showsWidgetContainerBackground == false,
                    ...
                )
       ...
}

WidgetSetStuff constructor sets some globals use elsewhere and has EmptyView() body.

@t9mike thanks, how do you compile your WidgetEntryView because .showsWidgetContainerBackground only available in iOS 17? and i have see those Xcode runtime error, so i tried a new approach but it couldn't work neither:

final class WidgetEnvironmentContext
{
    static let shared = WidgetEnvironmentContext()
    
    var showsWidgetContainerBackground: Bool = true
}

@available(iOS 17.0, *)
struct WidgetEnvironmentReader: View
{
    @Environment(\.showsWidgetContainerBackground) var showsWidgetContainerBackground: Bool
    
    var body: some View {
        
        WidgetEnvironmentContext.shared.showsWidgetContainerBackground = showsWidgetContainerBackground
        
        return Color.clear
    }
}

struct ExampleView: View
{
    var body: some View {
        ZStack {
            if #available(iOS 17, *)
            {
                WidgetEnvironmentReader()
            }
            
            Text("Shows Background: \(WidgetEnvironmentContext.shared.showsWidgetContainerBackground ? "YES" : "NO")")
        }
    }
}

showsWidgetContainerBackground variable is randomly wrong in this way, i am so confuse now, i think i just use separate view in my code

struct WidgetView: View
{
    var body: some View {
        if #available(iOS 17, *)
        {
            HeaderView()
        }
        else
        {
            FallbackHeaderView()
        }
        
        ...
    }
}

showswidgetcontainerbackground is iOS15+ according to Apple's docs. But I am seeing crash "Thread 1: EXC_BAD_ACCESS (code=1, address=0x0)" when run on iOS16. I have FB open on this:

FB12554533 (showsWidgetContainerBackground Environment variable crashes widget extension on iOS16 with Xcode 15)

I was tabling this issue for a few weeks in hopes it gets resolved. Feels like a bug that would hit a lot of people. But perhaps how I am using it is triggering the crash.

Ok, after a little digging(actually a lot...), i think i finally have a solution, just in case anyone dealing the some issue:

// First we create a fallback variable environment
struct WidgetEnvShowsContainerBackgroundKey: EnvironmentKey
{
    static let defaultValue: Bool = true
}

extension EnvironmentValues
{
    var widgetEnvShowsContainerBackground: Bool {
        set { self[WidgetEnvShowsContainerBackgroundKey.self] = newValue }
        get { self[WidgetEnvShowsContainerBackgroundKey.self] }
    }
}

extension View
{
    func envShowsContainerBackground(_ value: Bool) -> some View
    {
        environment(\.widgetEnvShowsContainerBackground, value)
    }
}

// Magic happens here
struct WidgetEnvironmentReader<Content: View>: View
{
    var content: () -> Content

    init(@ViewBuilder content: @escaping () -> Content)
    {
        self.content = content
    }

    var body: some View {
        if #available(iOS 17.0, *)
        {
            WidgetEnvironmentViewBuilder(content: content)
        }
        else
        {
            content()
        }
    }
}

extension WidgetEnvironmentReader
{
    @available(iOS 17.0, *)
    struct WidgetEnvironmentViewBuilder<C: View>: View
    {
        @Environment(\.showsWidgetContainerBackground) var showsWidgetContainerBackground
        
        var content: () -> C

        init(@ViewBuilder content: @escaping () -> C)
        {
            self.content = content
        }

        var body: some View {
            content()
                .envShowsContainerBackground(showsWidgetContainerBackground)
        }
    }
}

// Now we are free to use .showsWidgetContainerBackground in the older os version
@available(iOS 14.0, *)
struct WidgetView: View
{
    @Environment(\.widgetEnvShowsContainerBackground) var widgetEnvShowsContainerBackground: Bool
    
    var body: some View {
        Text("Background: \(widgetEnvShowsContainerBackground ? "YES" : "No"), \(Date(), style: .relative)")
    }
}

@available(iOS 14.0, *)
struct WidgetEntryView: View
{
    let entry: Entry

    var body: some View {
        WidgetEnvironmentReader {
            WidgetView()
        }
        .makeContainerBackground()
    }
}

I'm having the same issue with the same crash log. I filled a feedback with an example widget: FB12702894

I'm unable to support standby mode because of this too

Same problem here. The proposed solution works fine for now. Thanks

The below provides a quick and simple solution:

private struct _ShowsWidgetContainerBackground: EnvironmentKey {
    static let defaultValue: Bool = true
}


extension EnvironmentValues {
    var showsWidgetContainerBackgroundWithFallback: Bool {
        get {
            if #available(iOSApplicationExtension 17.0, *) {
                self.showsWidgetContainerBackground
            } else {
                self[_ShowsWidgetContainerBackground.self]
            }
        }
        set {}
    }
}

You can use the new environment key showsWidgetContainerBackgroundWithFallback in place of showsWidgetContainerBackground.