@protocol AProtocol <NSObject>
+ (NSSet<Class> * _Nullable)someClasses;
@end

class B: NSObject {}

class A: NSObject, AProtocol {
    static func someClasses() -> Set<NSObject>? {
        return [unsafeBitCast(B.self, NSObject.self)]
    }
}

NSSet<Class> *classes = [A someClasses];
BOOL doesIt = [classes containsObject:[B class]];
NSLog(@"%@", doesIt ? @"YES": @"NO");

class A: NSObject, AProtocol {
    static func someClasses() -> Set<NSObject>? {
        return [unsafeBitCast(AppDelegate.self, NSObject.self)]
    }
}