Can't import firebase in AppController
<p>I am getting this error "Use of '@import' when modules are disabled" when importing Firebase.</p>

<pre><code>#import "GameKit/GKLocalPlayer.h"
#import "GameKit/GKScore.h"
#import "GameKit/GKAchievement.h"

@import Firebase;

@implementation AppController
@synthesize viewController;
</code></pre>

<p>How can I import this properly?</p>