Apple began allowing ad-blockers on the iPhone and iPad versions of Safari in 2015. Devices running iOS 9 were – for the first time – permitted to add content blocking extensions to Safari.
Prior to this, the only way to block adverts was to “jailbreak” the devices, which involved replacing – or modifying – key components of the operating system with custom applications. Where subsequent security measures weren’t instigated, this resulted in their becoming easier for attackers to infiltrate.
Apple allowing ad-blocking Safari extensions negated the need to do this. At the same time, it ensured that the company could still make money from allowing advertising in apps.