bugfix: WebView not ignoring safe area in full-screen mode on iOS

[Erkko68]

When embedding a full-screen WebView in Compose Multiplatform on iOS, the view does not correctly ignore the safe area.

Even if the SwiftUI hosting side applies:

struct ContentView: View {
    var body: some View {
        ComposeView()
            .ignoresSafeArea(.all)
    }
}

…the WebView is still inset by iOS safe areas.

Before (safe area respected incorrectly):

After investigating related issues (#159), I found that the problem began after introducing a ScrollView wrapper. By default, UIScrollView always respects the safe area insets, even if Compose requests to ignore them.

Solution

The fix is to explicitly disable automatic content inset adjustment for the underlying UIScrollView. We can do this by setting:

contentInsetAdjustmentBehavior = platform.UIKit.UIScrollViewContentInsetAdjustmentBehavior.UIScrollViewContentInsetAdjustmentNever

After (expected full-screen WebView):

This allows to manage safe area handling (e.g., with .ignoresSafeArea(.all) or .ignoresSafeArea(.keyboard) or Compose itself) instead of iOS forcing additional insets.

This fix was tested with a modified version of HtmlWebViewSample.kt:

@Composable
internal fun BasicWebViewWithHTMLSample(navHostController: NavHostController? = null) {
    val webViewState =
        rememberWebViewStateWithHTMLFile(
            fileName = Res.getUri("files/samples/index.html"),
            readType = WebViewFileReadType.COMPOSE_RESOURCE_FILES,
        )
    val webViewNavigator = rememberWebViewNavigator()
    val jsBridge = rememberWebViewJsBridge(webViewNavigator)

    LaunchedEffect(Unit) {
        initWebView(webViewState)
        initJsBridge(jsBridge)
    }

    MaterialTheme {
        WebView(
            state = webViewState,
            modifier = Modifier.fillMaxSize(),
            captureBackPresses = false,
            navigator = webViewNavigator,
            webViewJsBridge = jsBridge,
        )
    }
}

Related Issues:
#159
#287

[Erkko68]

@KevinnZou Could you please rerun the workflows? Sorry about the earlier code style issues. I didn’t realize I could run the check locally with ./gradlew ktlintCheck. I’ve also rebased the previous commits to clean things up.