Apple has internally prototyped a stylus designed for its upcoming foldable iPhone, according to Bloomberg's Mark Gurman, but is unlikely to release it alongside the device's launch. The revelation matters because a stylus would set the foldable iPhone apart from existing iPhone models, yet practical design problems appear to be holding Apple back from bringing it to market straight away.

The prototype was reportedly "stubbier" than existing Apple Pencil models and, like them, would attach magnetically to the side of the phone for storage and charging. However, this attachment point would obstruct the fold when the device is opened but the stylus isn't in use, while the delicate foldable display also raises concerns about the pencil tip leaving marks, an issue Samsung has managed by limiting certain S Pens to specific foldable models. The foldable iPhone itself is expected to be unveiled on 9 September, alongside other rumoured updates including Apple Watch design tweaks and a new continuous heart-rate tracking feature.