Apple’s first foldable phone, iPhone Duo, is scheduled to become available Oct. 23, following preorders that opened Oct. 16. Apple says the device pairs a 5.4-inch outer display with a 7.6-inch inner screen and runs iOS 27.1; its launch markets include the United States, Mexico, Brazil and more than 70 countries and regions. Apple’s Oct. 5 developer guidance asked app makers to recompile with Xcode 27.1, test their software across Duo’s poses and orientations, and prepare new App Store screenshots. That gives the launch a second angle beyond hardware: developers have been preparing app layouts and store pages for the foldable form factor. Apple lists 28 additional markets for Oct. 30.