iOS 11 is downloadable from today and as usual the new version of Apple's flagship mobile software bestows upon us a bunch of fancy new features, including being able to customise the control centre, a new set of emojis and the swipe down on keyboard element. 

One new feature that has ad buyers anxious is the new ad tracking restrictions. They have added a 24-hour limit on ad targeting cookies, meaning it will be harder for advertisers to follow users around the web as data will not be allowed to be transferred from one website to the next.