Using an implementation of a Swift protocol within Obj-C

I'm trying to implement a mediator sort of pattern with a mixture of Swift and Obj-C. The issue I'm facing is with how to deal with using the Swift protocol implementation classes from Obj-C. Check out the code to see what I mean:

The Swift protocol and implementation of it:

@objc public protocol TheProtocol {
    func someMethod()
}

@objc public class SwiftClass: NSObject, TheProtocol {
    public func someMethod() {
        print("someMethod Swift")
    }
}

The ObjC-implementation of the protocol:

#import "SwiftAndObjC-Swift.h"
@interface ObjCClass : NSObject <TheProtocol>
- (void) someMethod;
@end


@implementation ObjCClass
- (void) someMethod
{
    NSLog(@"someMethod ObjC");
}
@end

My question is how is it possible to define some type in ObjC which is capable of referencing either a SwiftClass or an ObjCClass. For example this does not compile:

#import "SwiftAndObjC-Swift.h"
...
TheProtocol *p = [[ObjCClass alloc] init];
// Error: "Use of undeclared identifier TheProtocol"

This will compile:

@class TheProtocol
TheProtocol *p = [[ObjCClass alloc] init];

But not p can't be used:

@class TheProtocol
TheProtocol *p = [[ObjCClass alloc] init];
[p someMethod];
// Error: Receiver type "The Protocol" is a forward declaration"

(Adding casts to the assignment and/or method invocation doesn't help)

Any solutions?