skiptools / skip-web

Embedded WebView for Skip apps

SkipWeb

This is a free Skip Swift/Kotlin library project containing the following modules:

SkipWeb

Building

This project is a free Swift Package Manager module that uses the Skip plugin to transpile Swift into Kotlin.

Building the module requires that Skip be installed using Homebrew with brew install skiptools/skip/skip. This will also install the necessary build prerequisites: Kotlin, Gradle, and the Android build tools.

Testing

The module can be tested using the standard swift test command or by running the test target for the macOS destination in Xcode, which will run the Swift tests as well as the transpiled Kotlin JUnit tests in the Robolectric Android simulation environment.

Parity testing can be performed with skip test, which will output a table of the test results for both platforms.

skip-web's Issues

Cannot load local resources from WebView

It is common to want to load a locally-bundled HTML resource and load it in a web view, like so:

WebView(url: Bundle.main.url(forResource: "index", withExtension: "html", subdirectory: "about"))

This works in iOS, but on Android the load fails with the error:

The webpage at jar:file:/data/app/~~id/base.apk!/pgk/Resources/about/index.html could not be loaded because: 
net::ERR_UNKOWN_URL_SCHEME

The problem is that the Android web view doesn't automatically handle the jar:file: scheme.

If Skip resources were bundles as Android resources (which they aren't: they are traditional Java resources), then we might be able to transform local file loads into file://android_assets/ or file://android_res/ schemes, but this is expressly recommended against at https://developer.android.com/develop/ui/views/layout/webapps/load-local-content#antipatterns

The correct solution will probably be to implement a WebViewAssetLoader, as per https://developer.android.com/develop/ui/views/layout/webapps/load-local-content#assetloader . This would enable the customization of resource loading, and we could use the same mechanism to implement bespoke content loading schemes (e.g., loading content from a zip archive). Parity with WKWebView could be achieved through the WKNavigationDelegate decidePolicyFor delegate.

For the time being, the only workaround is to manually load the contents of the file into memory and load the HTML, like so:

WebView(html: try String(contentsOf: Bundle.main.url(forResource: "index", withExtension: "html", subdirectory: "about")))

This is very limited, though, because peer resources (e.g., scripts, stylesheets, and images) will not be resolved, so the HTML must be completely self-contained.