prefersStatusBarHidden not called

For swift 3, first, make sure that View controller-based status bar appearance is set to YES in your Info plist file

And then just add this to your view controller:

override var prefersStatusBarHidden: Bool {
    get {
        return true
    }
}

I hope this helps people in the future.

Firstly, View controller-based status bar appearance in the .plist file must be set to YES.

• If you want status bar to be hidden in the whole app:

For Objective-C:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    [application setStatusBarHidden:YES];

    return YES;
}

For Swift:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject:AnyObject]?) -> Bool {
    application.statusBarHidden = true

    return true
}

• If you want status bar is disappeared in Specify View Controller, in .m file, just implement:

For Objective-C:

- (BOOL)prefersStatusBarHidden {
    return YES;
}

For Swift:

override func prefersStatusBarHidden() -> Bool {
    return true
}

Figured it out. in info.plist file: view controller-status bar appearance should be set to YES