IB - Can't assign class for a View Controller

I'm quite new to IOS developpement, and I'm facing a problem here that I haven't encountered before. Here's what I have :

I created a project, added some ViewControllers attached to their own classes. But now, I just added a new ViewController in the storyboard. Then I created a new Objective-C class (with is a subclass of UIViewController). The problem is that in IB, I can't link the ViewController to the newly created class, as I simply don't have the class in the list provided by IB (see the image below). My new class is called MapShownViewController, but as you can see on the image, it's not available.

It worked well for all my other classes but not for this one.

Here's the MapShownViewController.h :

#import <UIKit/UIKit.h>

@interface MapShownViewController : UIViewController

@end

And the MapShownViewController.m :

#import "MapShownViewController.h"

@interface MapShownViewController ()

@end

@implementation MapShownViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

@end

Can someone explain me what I made wrong please ?