Tips for writing iOS content blockers - HelsinkiOS

content_blocker_tips.md

• read this first: https://www.webkit.org/blog/3476/content-blockers-first-look/
• start by adding a new extension target to your iOS app of type “content blocker”
• launch the app using the main target’s scheme + a call to SFContentBlockerManager.reloadContentBlockerWithIdentifier() with the extension’s id in application:didFinishLaunchingWithOptions: to auto-reload the blocker in development mode
• if you don’t call reloadContentBlockerWithIdentifier() then you need to switch the blocker off and on again in the Safari settings (stop the app in Xcode if the switch is not moving)
• use inspector from desktop Safari to inspect the Safari in the simulator in order to find specific things to block
• things like periods in the url-filter regexp need to be escaped with double backslashes, e.g. facebook\\.net
• if you use if-domain, it needs to be an array, even for one element
• domain foo.com might not match www.foo.com even though I think it’s supposed to (UPDATE: They've changed it in one of the betas, now foo.com only matches foo.com and to match all subdomains you need to use *foo.com - thanks @CraftyDeano!)
• remember that extensions are separate from the main app - use app groups and shared app group containers to share data between the app and the extension
• json file can be updated silently or even generated on the fly, just return whatever you want to in the beginRequestWithExtensionContext: callback
• look for critical errors in ~/Library/Logs/CoreSimulator/*/system.log