1. Backup entire device to iCloud or iTunes or both. (i did it for both just in case)

2. Go to Settings - General - Usage - Manage Storage (Storage not iCloud) you will see the size MW is stored on your device

3. Go into the details for MW and click on the button to "Delete App".

4. Make a note the size of MW and make sure that the amount of space taken up by MW has been freed up.

5. Restart your device

6. Once restarted, go to the App Store and download and reinstall MW.

7. MW should load faster and less lag afterwards

This is what I did for my devices and all seems to have gone smoothly.

Only thing not working still is when attacking someone from my "speed dial" list. "Revenge" works but "Attack" does not. It still just does not respond.

I hope that helps with those with an iOS device.