Responding to public sentiment, Apple announced in late December of 2017 that it would replace batteries on all out-of-warranty iPhone 6 and newer models at a reduced price of $29. This special pricing will end on December 31, 2018.
iPhone users who wish to take advantage of this special pricing can choose to send their phones in to a repair center or to make an appointment at an Apple Store or an authorized Apple service location. After December 31, 2018, promotional pricing for battery replacements will end.