After doing some research, it appears that the thing that violated Apple's TOS was a hidden feature to earn points in the app called BonusCoins. As you may know from installing apps like JunoWallet, FreeMyApps and various other pay per download apps, they are installed differently in that they install a profile in your iOS device instead of being installed through the AppStore. The reason behind this is that Apple does not like reward apps that pay users to download apps from the AppStore.
CheckPoints circumvented this by hiding this feature in their app under the "Anywhere" tab. With CheckPoints mainly being a reward app for scanning barcodes, it was probably hard for Apple to find out that CheckPoints violated their TOS. Obviously the downtime of CheckPoints meant that Apple caught on to CheckPoints tricks. With the new update/return of CheckPoints that was released today, BonusCoins was notably missing from the new update, which you can see from the screenshot below:
|Before update (left) vs After update (right)|
Also if you still use CheckPoints, would you like the page to be updated (post your responses in the comments below)? We seemed to get no responses from the last post so we thought we would ask again. Otherwise it will probably be kept open in case any of the barcodes returned but it won't be updated.