wkwebview-local-resources

iOS and macOS app with a WKWebView that loads local resources, based on one of my SO answers.

file://	app://

Currently supported:

• Local HTML, CSS and JS files shipped in the app bundle (web/)
• Remote HTML, CSS and JS files (as requested by edon2005):
  1. downloading custom_css_js.zip with URLSession and unzipping it with ZIPFoundation
  2. loading the unzipped files from Application Support in the WKWebView
• Two ways of loading those files, switchable in the app:
  • file:// – loadFileURL(_:allowingReadAccessTo:). Simplest option. The page has a null origin though, so fetch(), XHR and ES modules don't work.
  • app:// – a WKURLSchemeHandler serves the same files under app://local/. The page gets a real origin and behaves like it's on a web server. The bundled page fetches data.json to show the difference.
• Safari Web Inspector (Develop menu) in debug builds

Requirements:

• Xcode 26
• iOS 17+ / macOS 14+

How to use:

1. Clone project
2. Open LocalWKWebView/LocalWKWebView.xcodeproj (Xcode fetches ZIPFoundation via Swift Package Manager)
3. Pick your own team under Signing & Capabilities if you want to run on a device
4. Run on iOS or macOS and use the two segmented controls to switch between bundled/downloaded files and file:///app://

Where to look:

• WebView.swift – WKWebView wrapper for SwiftUI and the two loading methods
• LocalSchemeHandler.swift – the app:// scheme handler
• RemoteContent.swift – downloading and unzipping the remote files

On iOS 26 / macOS 26 and later SwiftUI has its own WebView and WebPage with support for custom URL schemes, so the wrapper isn't needed there.

Based on:

https://stackoverflow.com/questions/39336235/wkwebview-does-load-resources-from-local-document-folder/39459878#39459878