How to Call Objective-C Code from Swift: Friendship of Languages in iOS

Objective-C and Swift: Two Worlds, One Project

You write in Swift, but you have a library written in Objective-C, or old but proven code in ObjC. Sound familiar? Don't worry: Apple has provided an excellent mechanism for these two languages to work together. In this article, we'll break down how to call Objective-C code from Swift — quickly, simply, and without headaches.

This question is one of the most popular on Stack Overflow (thousands of views and hundreds of votes). And for good reason: the ability to integrate Objective-C into Swift opens up access to a huge legacy of libraries and code written over decades of iOS development. Let's finally figure out how it works.

What is a Bridging Header and Why Do You Need It?

The secret to the friendship between Swift and Objective-C is a special file called the Bridging Header. It acts like a translator: it tells Swift which Objective-C classes and functions are available and how to call them correctly.

When you create a bridging file, the compiler automatically picks it up and makes all declarations from Objective-C visible in Swift. You simply import the ObjC headers into this file — and you're done.

How to Create a Bridging Header in Xcode

The easiest way is to let Xcode do it for you. Simply add a new Objective-C file to your project (File → New → File → Objective-C File). Xcode will ask: "Would you like to configure an Objective-C bridging header?" — answer "Yes". After that, a file named YourProjectName-Bridging-Header.h will appear in your project.

If you are already working on a project and want to add the bridge manually, do this:

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• Create a new header file (File → New → File → Header File) and name it, for example, MyProject-Bridging-Header.h.
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• In the project settings (Build Settings), find the Objective-C Bridging Header parameter and specify the path to your file.
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Done. Now everything you write in this file will be available in Swift.

Writing an Objective-C Class and Connecting it to Swift

Let's create a simple class in Objective-C that will greet the user. First, the header file (Greeter.h):

// Greeter.h\n#import <Foundation/Foundation.h>\n\n@interface Greeter : NSObject\n\n- (NSString *)greetWithName:(NSString *)name;\n\n@end\n

And now, the implementation (Greeter.m):

// Greeter.m\n#import "Greeter.h"\n\n@implementation Greeter\n\n- (NSString *)greetWithName:(NSString *)name {\n    return [NSString stringWithFormat:@"Hello, %@! Nice to meet you.", name];\n}\n\n@end\n

Now, the most important part. Open your Bridging Header (e.g., MyProject-Bridging-Header.h) and add this:

// MyProject-Bridging-Header.h\n#import "Greeter.h"\n

That's it! Now you can use the Greeter class in Swift as if it were written in Swift:

// ViewController.swift\nimport UIKit\n\nclass ViewController: UIViewController {\n\n    override func viewDidLoad() {\n        super.viewDidLoad()\n        \n        let greeter = Greeter()\n        let message = greeter.greet(withName: "Alex")\n        print(message) // Prints: "Hello, Alex! Nice to meet you."\n    }\n}\n

Note: the method greetWithName: is transformed in Swift to greet(withName:). This is an automatic adaptation of method names from Objective-C to Swift style.

Working with Objective-C Frameworks and Libraries

Often you need to connect not your own code, but a ready-made library in Objective-C (for example, an old version of AFNetworking or CocoaLumberjack). This is even simpler:

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• Install the library via CocoaPods, Carthage, or SPM.
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• Import its headers into your Bridging Header.
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• Use