[mikehotel]

I was replying specifically to the first paragraph in the parent comment that other apps on iOS are not able to implement content blockers. Firefox Focus does appear to do just that. Obviously, not as effectively as uBlock Origin (thanks for testing!) but uBO isn’t yet available to install on Firefox on iOS.

(Edit since I can’t reply): Firefox Focus does appear to implement iOS content blocker since it appears as an option under Safari settings for content blockers.

[commoner]

Oh, I was using "Content Blockers" to refer to apps that implement Apple's Content Blocker API: https://developer.apple.com/documentation/safariservices/cre...

Firefox (standard and Focus) and other iOS browsers can block ads and trackers, but not as comprehensively as that API can. That API is limited to Safari due to platform restrictions, which I hope get removed in the future.

[mikehotel]

(And now I can reply, lol)

Firefox Focus appears under Safari settings > content blockers, along with more typical blockers like AdGuard. I think they both implement Content Blocker API.

[commoner]

The way Firefox Focus is implemented on iOS is a little complicated, since it's both a browser and a Content Blocker. As of 2017, Firefox Focus uses WKWebView as the webview component: https://github.com/mozilla-mobile/focus-ios/pull/507

WKWebView does not support the Content Blocker API. Ad blocking apps that use the Content Blocker API are only compatible with Safari and the SFSafariViewController component, which is very feature-limited and not suitable for a full web browser app:

- https://www.wwdcnotes.com/notes/wwdc20/10188/

- https://developer.apple.com/news/?id=trjs0tcd

As a workaround, Firefox Focus uses script injection to block ads and trackers within the browser part of itself, but the Content Blocker part of Firefox Focus only affects Safari:

- https://github.com/mozilla-mobile/focus-ios/blob/main/Blockz...

- https://github.com/mozilla-mobile/focus-ios/blob/main/Blockz...

- https://github.com/mozilla-mobile/focus-ios/issues/1761

However, both Firefox Focus and Safari (with the Firefox Focus Content Blocker enabled) score 78% on that test, so Firefox Focus might be good enough for web browsing on iOS if you're comfortable with its feature set and don't need the additional filter lists or custom rules that another third-party Content Blocker would offer.

Apple should still allow third-party browsers to use third-party Content Blockers, since this restriction is an unnecessary handicap for any non-Safari browser on iOS.

[markenqualitaet]

I think that means Safari can use Firefox Focus as content blocker. Not the other way around.