Convert NSString to FBSDKAccessToken
<p>Is there anyway to convert my NSString access token to type FBSDKAccessToken? I need it to be of this form to perform login with Facebook and Parse:</p>

<pre><code>[PFFacebookUtils logInInBackgroundWithAccessToken:AccessToken
    block:^(PFUser *user, NSError *error) {
        if (!user) {
            NSLog(@"Uh oh. There was an error logging in.");
        } else {
            NSLog(@"User logged in through Facebook!");
            NSLog(@"%@", user);
        }
}];
</code></pre>