There could be a few reasons, why you do not get push notifications. However, most of the time people have simply disabled notifications in the iOS settings.

1. Open your iOS settings and click on "notifications".
2. Tap on mysms to check, if the option "Notifications Center" is on. You can choose whether you would like to receive notifications as banner or alerts. In addition, it is possible to activate the badge app icon (red icon with number of new messages), the sound and the view in lock screen.
3. Now open the mysms app to receive push notifications again.