Does Apple allow mining from app? I have been looking into the feasibility of creating an app that mines cryptos. I have been searching iTunes for similar apps but none have come up where the miner is part of the app. Does anyone know if Apple allows mining from app? i.e would an app that does mining have even the slightest chance at being approved?
It seems unlikely that they'd allow that. App Store Review Guideline 2.4.2 provides:


  Design your app to use power efficiently. Apps should not rapidly drain battery, generate excessive heat, or put unnecessary strain on device resources.


Also, Guideline 3 seems relevant:


  If you want to unlock features or functionality within your app, (by way of example: subscriptions, in-game currencies, game levels, access to premium content, or unlocking a full version), you must use in-app purchase. Apps may use in-app purchase currencies to enable customers to “tip” digital content providers in the app. Apps and their metadata may not include buttons, external links, or other calls to action that direct customers to purchasing mechanisms other than in-app purchase.


(i.e. Apple must get a cut of all purchases.)

Or Guideline 3.2.2 (ii):


  Monetizing built-in capabilities provided by the hardware or operating system, such as Push Notifications, the camera, or the gyroscope; or Apple services, such as Apple Music access or iCloud storage.