Swift ObjectiveC Interoperability

The Objective-C Bridging Header

If you want to consume Objective-C code from Swift, you’ll need to use a bridging header.

Xcode offers to create the bridging header for you the first time you
add an Objective-C file to a Swift app target. If you accept, it names
the file after your product module (YourProject-Bridging-Header.h) and
fills in the build setting described below, so in most cases there is
nothing else to configure.

If you didn’t accept that offer, you can create the header yourself with
File -> New -> File ... -> iOS -> Source -> Header File. You’ll want
to name this file something like YourProject-Bridging-Header.h, but
the name doesn’t actually affect the build process. You’ll need to
specify its path, relative to your project, in the Objective-C
Bridging Header setting under Swift Compiler - General in your
target’s Build Settings.

You will then #import every Objective-C header you want to expose to
Swift in this file.