iPhone Duo apps pass 100,000 optimized mark in two weeks

Apple announced that iPhone Duo apps fully optimized for the new foldable display have passed the 100,000 milestone just two weeks after the hardware hit shelves. Built specifically for early adopters seeking expansive screen space, the most notable improvement is complete full-screen scaling with vertical toolbars, though owners will still encounter older apps trapped in centered windows surrounded by substantial unused borders.

Susan Prescott, Apple's Vice President of Worldwide Developer Relations, confirmed the milestone on Friday, November 7, noting that developers have adopted the foldable format rapidly, with thousands of updated titles going live on the App Store each day.

How Apple Ranks iPhone Duo App Optimization

Not every app running on the inner screen delivers the same user experience. Apple separates software compatibility on the iPhone Duo into three distinct tiers based on the software development kit used by developers:

• iOS 26 SDK or earlier: Unmodified legacy apps display as a standard phone window centered on the large internal display. The remaining display area sits idle as blank framing around the interface.
• iOS 27 SDK: These apps expand to fill the vast majority of the foldable screen, but the interface still leaves blank margin space along the right edge where the status bar sits.
• iOS 27.1 SDK or newer: This tier represents what Apple officially classifies as optimized. Software compiled on this kit stretches across the entire inner display and shifts navigation bars and toolbars into vertical layouts better suited for wide-aspect dual-pane viewing.

The 100,000 figure announced by Apple exclusively counts apps targeting iOS 27.1 or newer. For early adopters, that distinction means genuine full-screen utility rather than basic window scaling across a significant portion of everyday downloads.

If you have picked up a foldable device, how much does unoptimized letterboxing affect your daily workflow, and which everyday app do you still want to see redesigned for a wide-screen layout?