Does your app need iPhone Duo work?

That depends on how much your app matters to the kind of person who buys a new flagship phone on launch weekend. Doing nothing is a legitimate choice: an app built against an older SDK keeps running, shown at a familiar phone size. It does not crash and it does not disappear. What it does is look dated beside a competitor that fills the screen, which is a commercial problem rather than a functional one. If your app is how customers reach your business, that gap is the cost of waiting.

It is the one step that is riskier done halfway than not at all. Building against the older SDK keeps your app in a compatibility presentation that hides most layout problems. Rebuilding against iOS 27.1 opts you into the full display and makes you responsible for the geometry at its edge: the hinge, the asymmetric safe areas and the vertical bars. An app that takes the SDK bump without the layout work behind it can look worse than one that stayed put. Treat the rebuild as the start of the work, not the whole of it.

Often, yes, and we would rather you did than buy something you do not need. Four changes account for most of the visible improvement and none of them need the new APIs: remove hard-coded widths, stop relying on orientation locks, treat safe-area insets as asymmetric, and drop layout branches gated on device idiom. All four are documented on this site with the commands that find them. Hire help when you want the problem list verified against your actual code before you commit a sprint to it, or when the fold APIs need a native module your team has not written before.

Nobody knows, and anyone quoting you a figure for a device that has not shipped is guessing. Apple does not publish unit sales. We would not base the decision on a number that does not exist yet. The more useful question is whether the people who buy a first-generation folding iPhone overlap with the customers you care about, because those buyers tend to be early adopters who are vocal about what works badly.

Set aside the cost of finding out, and defer the rest. A fixed-price audit is $299 USD and turns an open-ended question into a written list with an effort estimate against your own code. You can then either hand that list to your own team or take a fixed quote for the work. Implementation starts at $1,999 USD and is quoted from the audit rather than from a price list, because the number depends on your code and we are not willing to invent one.