Name of Swift class when exposed to Objective-C code does not respect the @objc renaming

Note: Things have change since this answer was first written - see updates at the end!

Yeah, this does seam to be a bug... though, controlling Obj-C runtime names of methods does work:

Say we define a pair of minimal Obj-C and Swift classes that interact with each other:

Foo.swift

import Foundation @objc(SwiftFoo) class Foo { // inheriting from NSObject makes no difference in this case @objc(postcardFromSwift) class func postcard() -> String { return "Postcard from Swift!" } @objc(getMailInSwift) class func getMail() { if let hello = NSBar.postcard() { // NSBar is an Obj-C class (see below) println("Printed in Swift: \(hello)") } } } 

NSBar.h

#import <Foundation/Foundation.h> @interface NSBar : NSObject + (NSString *)postcard; + (void)getMail; @end 

NSBar.m

#import "NSBar.h" #import "ObjS-Swift.h" @implementation NSBar + (void)getMail { // notice that I am not referring to SwiftFoo in spite of @objc(SwiftFoo) printf("Printed in Objective C: %s", [[Foo postcardFromSwift] UTF8String]); } + (NSString *)postcard { return @"Postcard from Objective C!"; } @end 

If we now call their class methods, say, from main.m:

#import <Cocoa/Cocoa.h> #import "NSBar.h" #import "ObjS-Swift.h" int main(int argc, const char * argv[]) { // notice that I am not referring to SwiftFoo in spite of @objc(SwiftFoo) [Foo getMailInSwift]; [NSBar getMail]; return NSApplicationMain(argc, argv); } 

This prints the following:

// --> Printed in Swift: Postcard from Objective C! // --> Printed in Objective C: Postcard from Swift! 

But it shouldn't have! Foo should only be visible to Obj-C as SwiftFoo since that is what @objc(SwiftFoo) is promising to do. Indeed, using SwiftFoo triggers the Use of undeclared identifier compiler error instead. The fact that this did work for method names, leaves little doubt that this is a bug. I am just amazed that you seem to be the first to ask about it! Plus one for that!

And yes:

// <#ModuleName#>-Swift.h SWIFT_CLASS("SwiftFoo") @interface Foo + (NSString *)postcardFromSwift; + (void)getMailInSwift; 

... does seam to be inverted for the class name, yet this is how that macro works – see WWDC video Swift Interoperability In Depth (c. 45 min and c. 48 min into the video). The relevant documentation is Exposing Swift Interfaces in Objective-C.

Xcode 7 beta 4

The issue is now fixed (thanks to @ScottBerrevoets for the comment).

Xcode 7.1

(thanks to @Pang for the comment)

@objc class C { } // error: only classes that inherit from NSObject can be declared @objc 

Currently (in XCode8) this seems to have been addressed.

Defined in XYZLogger.h and XYZLogger.m

NS_ASSUME_NONNULL_BEGIN NS_SWIFT_NAME(Logger) @interface XYZLogger : NSObject + (void)verbose:(NSString *)logString; + (void)debug:(NSString *)logString; + (void)info:(NSString *)logString; + (void)warn:(NSString *)logString; + (void)error:(NSString *)logString; @end NS_ASSUME_NONNULL_END 

Used in objc like this:

[XYZLogger debug:@"Hi from objective C"]; 

Used in Swift like this:

Logger.debug("Hi from swift");