Update your apps to use new features, and test your apps against API changes.
The iOS 12.1 SDK provides support for developing iOS apps for iPhone, iPad, or iPod touch devices running iOS 12.1.1. The SDK comes bundled with Xcode 10.1 available from the Mac App Store. For information on the compatibility requirements for Xcode 10.1, see Xcode Release Notes.
iOS 12.1.1 requires that publicly-trusted Transport Layer Security (TLS) server authentication certificates issued after October 15, 2018 meet the Certificate Transparency policy to be evaluated as trusted on Apple platforms. (41175212)