我的有效负载是否格式错误，在后台调用didReceiveRemoteNotification？

According to these (and many more) questions on SO:

• stackoverflow.com/questions/18856204
• stackoverflow.com/questions/20741618
• stackoverflow.com/questions/31967093
• stackoverflow.com/questions/19068762
• stackoverflow.com/questions/30936507

I figured out, that the main keys for silent push-notification and for the method

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler

to be called in the background are: the payload, iOS version > iOS 7, enabled background mode with "Remote notifications" and registering push notifications in
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
method.

I did all of those things, but the method mentioned above, that supposed to be called in the background, is only being called while the app is foreground. This is how I form my payload in php:

$contents = json_encode(array(
            'aps'   => array(
                'content-available' => '1',
                'sound' => '',
                'alert' => '',
            ),
            'where' => array(
                'deviceType'    => array(
                '$in'   =>  array('ios', 'android'),
                ),
            ),
            'data'  => array(
                'title' => $this->subject,
                'msg'   => $this->message,
                'date'  => date('d.m.Y H:i', time() + (60 * 60 * 2)),
                'key'   => APPKEY,
                'ids'   => $ids,
            ),

        ));

and this is what I get in Xcode console, as I am able to NSLog the payload when app is in foreground:

{
    aps =     {
    };
    date = "21.10.2015 11:01";
    ids =     (
        259,
        257,
        256,
    );
    key = xpy3fq4t3wn9;
    msg = test11;
    title = aatest1;
}

What am I doing wrong? Why isnt "content-available = 1" in Xcode console? Or is there any other reason why appDelegate method isnt being called in background?

Im using iOS 8.1.3, Parse as Push-Notification provider.