Apple's iPhone Duo is the first iPhone that can run two apps side by side, but anyone expecting the sort of freedom that Split View offers on iPad might want to temper their expectations.
Apple's iPhone Duo marketing materials talk up app pairs and side-by-side windows, but it doesn't mention anything about resizing them. There's a reason for that.
If you put two apps side by side on the iPhone Duo's 7.6-inch foldable display, you can't drag the divider between them to make one app take up more space than the other. It's a fixed 50/50 split, regardless.
That's likely to be a disappointment to anyone who's used Split View on the iPad. Indeed, iPad owners have been able to resize apps in Split View when in landscape mode ever since 2015 when iOS 9 introduced the feature.
So why does Apple not let you resize apps on the iPhone Duo? It's likely down to the device's display geometry.
Both the inner and outer displays share the same 1:1.4 aspect ratio, and each half of the inner display works out to roughly the same size and shape as the outer screen. So an even split gives each app a canvas it already has to support, with the divider sitting neatly on the fold. (The only exception to this, it seems, is when watching a TV show or movie above another app in portrait mode; based on Apple's promo videos, Apple TV content is shown in its proper aspect ratio and the lower app is allowed to rise above the fold.)
If you were able to drag the boundary around, not only would it create a bunch of in-between sizes that wouldn't fit neatly on the outer screen, it would also be a nightmare for developers to build support into their iPhone apps.
Despite the lack of resizing capability, the iPhone Duo's foldable screen still has a lot of benefits. It allows you to quickly swap between apps, open two windows of the same app, and have a conversation over Messages while looking at another app's content, in both landscape and portrait modes. You can also save pairs of apps to come back to later.
Using apps side-by-side on iPhone Duo. So unfortunately, you can't change the app size when you use split view on the iPhone Duo. Only 1:1. 画面分割した際のアプリサイズは変えられない仕様です🥲 pic.twitter.com/1K1peXeivK — g.O.R.i（ゴリミー管理人） (@planetofgori) September 10, 2026
Apple's first iPhone with a foldable display was always going to having a learning curve, especially for users coming from the iPad. With a starting price of $1,999, iPhone Duo pre-orders begin Friday, October 16, with availability starting Friday, October 23.
