WWDC 2014 Session 206: Introducing the Modern WebKit API

Architecture

• API is identical on OS X and iOS.
• Uses the fast Nitro JS engine on iOS (unlike UIWebView), including fourth tier LLVM JIT.
• WKWebView has its own process(es), separate from the main app process.
• Each page gets its own process up to an unspecified limit, at which point pages start sharing processes.

WKWebView

• WKWebViewConfiguration class encapsulates all configuration so that it can be shared among multiple instances of WKWebView.
• Properties (title, URL, loading, estimatedProgress) are KVO-compliant.

Customizing Page Loading

• Hook into page loading, page actions, and network responses using methods in the WKWebViewNavigationDelegate protocol.

Gestures

• allowsBackForwardNavigationGestures property enables left/right swipe gestures for navigation.
• Set allowsMagnification property on NSScrollView for double tap and pinch to zoom. UIScrollView does this automatically with no additional configuration.

Customizing Webpage Content

• Use WKUserContentController (userContentController property on WKWebViewConfiguration) to inject user scripts into web pages and register handlers for script messages.
• User scripts (see WKUserScript) are scripts written in JS and are generally used to modify the DOM.
  • Debugged using the Safari web inspector.
• Script messages (see WKScriptMessage) are sent as JSON from the web page to your app and are automatically converted into Objective-C types.

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The modern WebKit API, including WKWebView and all associated classes are part of the open source WebKit project. The source code for these classes can be found here.