Using Swift from Objective-C

There are few basic steps to use a Swift class from Objective-C. Most of the documentation around skip or misconvey the actual usage. The first thing to know is that, the first time you add any Swift or Objective-C file to your project, Xcode will prompt you to add a bridge-header.h file. This is completely irrelevant to use Swift from Objective-C because an invisible file named YOUR_PROJECT_NAME-Swift.h is automatically created for you when you build the project.

The last sentence is a very important point, in order to get access to this invisible file you have to add the @objc tag to the classes, methods, properties, etc. that you want to expose to Objective-C and then run the build command (i.e. ⌘ + b).
A class supposed to be available in Objective-C will look like this:

@objc class Person {

After you run the build you can import the invisible file header into the .m files and use then the class, methods and properties as usual in Objective-C

import "YOUR_PROJECT_NAME-Swift.h"

Person *person = [[Person alloc] init];

The YOUR_PROJECT_NAME-Swift.h file must be imported in all the files you are planning to expose the classes, methods, properties, etc. defined in Swift and tagged with the tag @obj.