To get the latest events, fixes and content, you must make sure that your game is up to date. Remember to update your software regularly, so that you always have the latest version of the game. Or better yet, have your device do it automatically, so you don’t have to worry!
To check for updates on iOS:
Open the App Store.
In the bottom right, there is a button labeled ‘Updates’. If you tap here, all your installed apps will show up. You can open any app to update it individually, or press the ‘Update All’ button.
Depending on your device settings apps may only update if the device is connected to a Wi-Fi network. Once you have installed the updates, please restart the device: https://support.apple.com/en-us/HT201559