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

Question

Given a declaration of a Swift class like

@objc(NSFoo) public class Foo {
   public func bar() -> () {}
}

I would expect, from my reading of

Answer 1

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");

Answer 2

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