Ad blocking extensions have been possible on Safari for Mac for a
long time, but plugin architecture for Safari on iOS is much more
limited. With iOS 9, Apple has added a special case of extension
for ad blockers. Apps can now include “content blocker” extensions
that define resources (like images and scripts) for Safari to not
load. For the first time, this architecture makes ad blockers a
real possibility for iOS developers to make and iOS customers to
install and use.
The inclusion of such a feature at this time is interesting. Apple
is also pushing its own news solution in iOS 9 with the News app,
which will include ads but not be affected by the content blocking
extensions as they only apply to Safari. There is also clearly the
potential for Safari ad blockers to hurt Google, which seems to be
a common trend with Apple’s announcements recently…
I think the timing with News is coincidental. But this is huge news — there are way more iOS Safari users than OS X Safari users.