Start using Swift code in your Objective-C project

If you decided to start using Swift in your existing Xcode project, it can become a pain if your project is large and contains multiple targets. Follow steps below to be able to use Swift classes in your Objective-C code:

1. Create a new *.swift file in your Objective-C project, or drag a .swift file with Finder
2. Xcode prompts you to create an Objective-C bridging header file. Confirm it or add the bridging header manually
3. Use @objc attribute for your Swift class:

   import Foundation
   
   @objc class YourController: UIViewController {    
   }
   
   

4. In Build Settings of your project check parameters below:
   Defines Module : YES
   Install Objective-C Compatibility Header : YES => Once you’ve added *.swift file to the project this property will appear in Build Settings
   Objective-C Generated Interface Header : $(PROJECT_NAME)-Swift.h
5. Import Swift interface header in your *.m file like this:

   #import "YourProject-Swift.h" // $(PROJECT_NAME)-Swift.h