Safari Application Extensions

Overview of Extending your App with Safari App Extensions

A Content Blocker app extension customizes the way Safari and Safari View Controller handle your content. The extension can tailor your content by hiding elements, blocking loads, and stripping cookies from Safari requests. Your app extension provides content-blocking rules to tell Safari how to manipulate content.

Content-blocking rules are created in a structured format ahead-of-time, declaratively, rather than running extension-provided code at the moment a decision about blocking needs to be made. WebKit compiles the ruleset into a bytecode format that it can process efficiently at runtime, reducing latency between when a page request is created and when it is dispatched over the network. Safari does not request undesired content. By avoiding unnecessary or unwanted downloads, Safari uses less memory and has better performance.

Safari on macOS and Safari on iOS use the same format for content-blocking rules, an array of JSON objects. Each rule contains a trigger dictionary and an action. The trigger specifies when a rule applies, and the action specifies what Safari should do when a match is found.

Begin creating your content-blocking rules by examining the web page resources with Web Inspector. After identifying the elements you want to block, create content-blocking rules that match only those target elements and choose the actions to perform.

Capabilities

• Customize web pages
• Block loading of resource of element
• Add toolbar buttons
• Display popovers
• Add items to context menus on web pages

Benefits

Built Using App Extension

• Developed using Xcode
• Run native code

Distributed with your app

• Sold through the App Store
• Same Version as your app

Type

• Content Blockers
• Page modification and communication with native code
• Extending Safari’s UI

Why are content blockers needed?

Apps will tell safari the content they want to block ahead of time instead of safari consulting with the app during the actual loading process. This model is fast and efficient because it doesn’t have to consult with the app during loading, and the content blockers are compiled into byte code that can be evaluated very efficient.

Content blockers identify the subset of content or resources on a page doesn’t show or even load.

Using a Content Blocker extension, you provide Safari with content-blocking rules that specify how Safari treats content such as images, scripts, and pop-up windows.

There are two main ways to block the using a content blocker:
1) Hide element on a page
2) Block resource from loading altogether

What content blocker can do?

1. Hide element

Each content blocking is JavaScript Object Notation (JSON).
Object content action and trigger dictionaries: The “action” dictionary contains a “type” key with the value “block”, and the “trigger” dictionary contains a “url-filter” key with the value.