The company published preview documents for Safari 9 detailing the 'Content Blocking Safari Extension' at its developer conference earlier this week.
Apple wrote: "Content Blocking gives your extensions a fast and efficient way to block cookies, images, resources, pop-ups, and other content."
That means Safari users could block ads and a wider range of site content simply by downloading a browser extension. The blocking feature is already available on Safari on desktop.
The number of users installing adblockers equates to almost 5% of the entire internet population
Apple hasn't released further detail about content blocking extensions, but one adblocking service, Adblock Plus, suggests the technical changes will actually make adblocking more difficult.
The company's comments were initially interpreted as a complaint that Apple was encroaching on its business, but it has denied this is the case.
Developer Sebasian Noack wrote: "We are not crying about Apple taking over our business. They don’t. We merely [point] out that the new API they are going to provide us with, which eventually is going to replace the old one, might be inferior and putting adblocking in general – not only in our case – at risk."
Impact on mobile advertising
Until developers begin building ad-blocking extensions for Safari on iOS 9, it is hard to predict the impact on mobile ad revenues.
Adblocking across devices has, until recently, been the preserve of more 'techy' consumers.
But according to a report last year from PageFair and Adobe, the number of users installing the technology equates to almost 5% of the entire internet population.
One key reason is the growing popularity of adblocking extensions on desktop browsers, such as Google Chrome and Safari. Another might be the lasting impact of piracy on a generation accustomed to accessing online services at no cost.
The report suggests adblocking on mobile is currently "relatively low", but has warned this could change.
Steve Chester, head of data and industry programmes at the IAB, told Marketing: "It's challenging, because this brings the facility to block on Safari on mobile en masse."
According to the PageFair report, the majority of users installing adblockers are also unwilling to pay for the services which rely on those ad revenues - raising questions over how publishers are meant to make money.
Chester said: "A good proportion of people understand that ads exist because [those] pay for the content and services they enjoy.
"The unanswered questions is that if a growing user base will not pay for content, how do you deliver those services without an alternative model?"
Chester pointed to experiments such as Google Contributor, which allows users to pay to remove ads, but notes that the "jury is still out on that".
The IAB and other industry bodies have championed "informed control", where a user understands the consequences of behaviour such as ad blocking. The question is, since these technologies are adopted by the most tech-savvy users to begin with, whether this will be enough.
Privacy or competitive advantage?
Apple is not commenting on why it is permitting ad blockers on mobile but some have interpreted the move as an attack on its nearest competitor, Google.
Unlike Apple, Google’s primary revenue source lies in online advertising, which may be one reason it is increasingly unfriendly to adblockers.
Google began to remove adblocking services – including the popular Adblock Plus – from its Play store in 2013. Adblock Plus remains unavailable on the Play Store, though a beta version is available for Android from its site. Earlier this year, it emerged that Google, Microsoft and Amazon may be paying Adblock Plus to whitelist their ads.
Apple CEO Tim Cook has previously made noises about the importance of user privacy, and the company is known for its stance against tracking in any form.
But given the three firms comprise Apple’s biggest competitors in the tech sector, cynics have suggested that the Safari move is unlikely to be motivated by concern for user privacy.
Steve Chester noted: "People don’t block ads because of privacy – they block because they don’t want to see ads. The privacy debate is important, but it’s not [applicable] for the majority of people blocking ads."