How to integrate Objective-C and Swift?

Question

I am doing a project on Swift and would like to use some files in Objective-C. It is possible to do this?

In case I installed using the Cocoa Pods, I don’t know if it influences anything.

Answer 1

Using classes in Objective-C in the Swift

Creating a Bridging Header

When you drag the files to the project

By dragging a .m The Xcode going will most likely show you this window:

Just answer Yes and the Xcode does all the magic for you!

When you use Cocoa Pods

(or when the Xcode doesn’t work its magic)

• Create a Header of Objetive-C making ⌘+N and selected Objective-C Header.
• Go to the project settings > Build Settings > Swift Compiler - Code Generation and name your Header.

You can do as in this picture: But don’t forget to change the beginning of Path for $(SRCROOT) to ensure that the code compiles on other machines.

Importing classes Objective-C

Just include in your Bridging Header the Imports in the standard Objective-C, for example, to import the class XMLDictionary use

#import "XMLDictionary.h"

Calling methods of Objetive-C in Swift

Now just use the methods, no need to import anything into your classes Swift, it’s that simple!

Patchwork:

• More information on this subject and source of the images in that question (in English).
• It is interesting to follow the Xcode name convention and name your bridging header of Meu_Projeto-Bridging-Header.h where your project is called Meu Projeto (trade spaces for _.

For the sake of completeness there goes the answer to the mirror question:

Using class Swift in Objective-C

Use classes Swift in Objective-C is even simpler!

If your class inherits from NSObject

Just import "MeuProjeto-Swift.h" in the Objective-C

If that file doesn’t show up

• In Build Settings > Packaging:
  • Marque Defines Module as Yes
  • Ensure that Product Module Name possesses only alpha-numeric characters
• In Bulid Settings > Apple LLVM 6.0 - Language - Modules:
  • Marque Enable Modules (C and Objective-C) as Yes

Important: it is normal that file is not listed, you should be able to import it anyway.

If your class nay inherits from NSObject

• Prefix @objc before class in your class Swift
• Create a class method to be your constructor Example:

import Foundation

@objc class ObjetoSwiftPuro {

    var nome: String
    init(nome: String) {
        self.nome = nome
    }

    // Método de classe para retornar instância nova
    class func novaInstanciaNomeada(nome: String) -> ObjetoSwiftPuro {
        return ObjetoSwiftPuro(nome: nome)
    }
}

Full Disclaimer: the part about using Swift in Objective-C was inspired by @Logan with participation of @Tomášlinhart.