Frostbite wrote on their blog that they have began construction on a tech demo of BattleField 4 on iPad, utilizing Apple's new low-level graphics API Metal to port the console game to iOS. Frostbite has released two screenshots that depict the game functioning within a mobile setting.
With complex graphics, and a high-performance demand, BattleField 4's console-quality has historically been too complex for mobile iterations, but standards for gaming are changing thanks to Metal. The API efficiently allocates resources in a low-level GPU environment in order to increase performance and distribution of power for iOS applications. Hailed in July by Unity, Metal is now endorsed by Frostbite, with reports of high quality performance during BattleField 4 testing.
According to Frostbite, "hardware and software limitations forced us to either scale down the number of objects and their complexity to retain visual fidelity, or accept lower visual fidelity to cope with a larger number of objects. This all changed when Apple introduced Metal, their new low-level graphics API, which allowed us to make full use of the hardware."
No information regarding a future iOS release has yet to be announced, and as no video depiction of BattleField 4 on iPad has currently been released, it appears that the project is at an early stage of production.