While there may be debate about whether iOS 19 will be a UI revolution or evolution, there does seem to be a consensus view on app icons. Namely, that they are likely to switch from squircles squares with rounded corners to circles.Whether one looks better than the other is of course a matter of subjective judgement. But there is a small problem with circular icons If you look at current iPhone icons, they can be broadly divided into three:An underlying square designAn underlying circular designNo inherent shapeLet me show you what I mean by this. The Home and Wallet apps are a good example of an underlying square design the graphics are square (or at least rectangular, tending to square), so can be as large as desired within the squircular space:In contrast, some apps use circular graphics, with Safari and Spotify good examples. Theres again no real constraint on the size of a circular graphic within a squircle we can see here that Apple has chosen to use most of the available space while Spotify uses a bit less of it:Finally, there are graphics which simply fill the available space, and have no inherent shape. The Notes and Map icons are examples of these:If iOS 19 adopts circular icons, then clearly theres no issue with circular app graphics as now, these can use as little or as much of the available space as desired. Similarly, graphics which fill the space can adapt to any shape.But for square graphics, they will have to shrink to fill the available space within a circular shape. This could make them harder to spot at a glance. We can see this with the Reddit and Slack icons in our mockup at the top of the piece.Of course, Im in no way suggesting this is a major usability barrier. Developers would be free to rework their icons into circles, or to fill the space. But I would argue that circular icons are just a little less space-efficient.Do you have a preference for squircles over circles? Please share your thoughts in the comments.Highlighted accessoriesAdd 9to5Mac to your Google News feed. FTC: We use income earning auto affiliate links. More.Youre reading 9to5Mac experts who break news about Apple and its surrounding ecosystem, day after day. Be sure to check out our homepage for all the latest news, and follow 9to5Mac on Twitter, Facebook, and LinkedIn to stay in the loop. Dont know where to start? Check out our exclusive stories, reviews, how-tos, and subscribe to our YouTube channel