After updating to iOS 12 and a variety of newer beta versions, Square (and other apps) have been crashing continuously at launch or been very slow to respond. Additionally after fixing the app crashes the Contactless Chip Card Reader failed to connect.
Here were the steps I took to resolve this issue. Hopefully they are helpful to anyone else having similar issues.
1) Reinstall Square (Point of Sale) app fresh.
To resolve the app crash issues, delete the app off your phone (hold it down until it wiggles, then press the x icon in the upper left.
Go to the app store and download Square.
Sign back into your account.
2) Delete your contactless reader and re-add it again in BOTH Square app and under Bluetooth settings.
To resolve issues with the contactless reader connecting, go into the Square app, click your Settings. Click Card Readers. Select your existing card reader and choose "Forget This Reader".
Then go out of the Square app and go into your Settings. Click Bluetooth. Find your square contactless reader from the list (Name should be something like Square Reader 399). Then choose the i icon on the right and choose "Forget this Device.
Finally go back into the Square app, click Settings, Card Readers, then press "Connect a Reader" and follow the steps to re-add your reader.
By doing these two steps I was finally able to get Square up and running after the iOS 12 issues.
