That is not the same as these statements, both of which are incorrect and will not work:

An older binary's textual interface is forward-compatible with newer Swift compilers.

A new compiler is backward-compatible with the textual interface of a binary compiled by an older compiler.

The following are equivalent statements with the directionality flipped, and accurately represent what will work:

The language is important, because the concept of backward- and forwards-compatibility are relative terms, and the direction of that relativity between compiler and library matters. Part of what might have confused you is the specific language used to discuss these issues. I also found this interesting explanation in this great Apple developer forum answer that explains the relative terms of backward- and forwards-compatibility. swiftinterface file may be using a new syntax that is unknown to older compilers. Module interfaces generated by a given version of the Swift compiler are guaranteed to be imported by any future Swift compiler that supports the -swift-version that it was compiled with. Module interfaces aren't backward-compatible, only forward-compatible. swiftmodule files.Īnd since they behave like source code, future versions of the Swift Compiler will be able to import Module Interfaces created with older versions.

Library evolution support allows developers of binary frameworks to make additive changes to the API of their framework while remaining binary compatible with previous versions.īinary frameworks built with Module Stability have Swift Module Interfaces, a text-based definition of their framework's APIs as part of generated.

Module stability allows Swift modules built with different compiler versions to be used together in one app.

What is Module Stability in Swift and why should you care? by Donny Wal.

Binary Frameworks in Swift WWDC 2019 session.

Library Evolution in Swift article by.

Let's step back and check the exact promise of Module Stability.

What is the minimum Xcode version the library supports?.

What is the minimum OS version the library supports?.

The vendor of the binary framework should have documented:

Old xcode versions