プロトコルに準拠したid型の利用

Bridging-Header.h

#import "ObjcClass.h"

main.swift

let objectConformsSomeProtocol = ObjcClass.objectConformsSomeProtocol()
objectConformsSomeProtocol?.doSomething()

ObjcClass.h

#import <Foundation/Foundation.h>
@protocol SomeProtocol
-(void)doSomething;
@end

@interface ObjectConformsSomeProtocol:NSObject<SomeProtocol>
@end

@interface ObjcClass:NSObject
+(id<SomeProtocol>)objectConformsSomeProtocol;
@end

ObjcClass.m

#import "ObjcClass.h"

@implementation ObjectConformsSomeProtocol
-(void)doSomething{
	NSLog(@"Do Something.");
}
@end


@implementation ObjcClass

+(id<SomeProtocol>)objectConformsSomeProtocol{
	return [ObjectConformsSomeProtocol new];
}

@end