This always seemed the right answer. Prompt the user "App Foo wants to use calendar/pictures/location" and then you have options like "Allow", "Deny", "Allow w

This always seemed the right answer. Prompt the user "App Foo wants to use calendar/pictures/location" and then you have options like "Allow", "Deny", "Allow with filtered data" (i. e. select just a few photos out of the gallery), or "Allow with bogus data" (generated gibberish that goes away after use)