The calendar app that also mined cryptocurrency was removed from the app store by Apple because it was not power efficient.
Calendar 2, reports The Verge, mined the cryptocurrency Monero in the background, but Apple determined that this negatively impacted devices that were using it.
Qbix, the company behind the app, convinced users to allow the mining activity by offering premium features in return. However, several bugs caused the miner to run even if a user opted out, and one reported the app using 200% CPU.
The app earned around $2,000 worth of Monero over three days.
The app is available on the app store again after removing this feature, and is offering users a year of premium features for free.