Apple has detailed how its iOS 8 Controller Forwarding will work, turning an iPhone with a gamepad accessory into a wireless remote for iPad and Mac games. The new feature, which builds on iOS' existing support for third-party gaming controllers, is one of a number of tweaks and improvements to the Game Controller framework, revealed at WWDC 2014 this week.
As it stands, Apple supports three types of gamepad with iOS. The standard has the usual D-pad, four button cluster, and two shoulder buttons; an extended version adds analog sticks and extra buttons. Finally, there's a standalone controller, which has the same control features but which connects wirelessly rather than seeing the iPhone dock into it.
With iOS 8, however, the iPhone will be able to connect over Bluetooth or WiFi to a nearby iPad or Mac and act as a controller for a game running on them.
The two devices need to be signed into the same iCloud account for the system to work; assuming that's the case, a D-pad symbol will appear on the iPhone's lockscreen when it's fitted into a gamepad accessory, and swiping it up will automatically start the connection.
For developers, Apple said, there's no extra work to be done in adding the support to their games. As long as they've added the correct controller support code, the iPhone will simply be recognized as a standard wireless controller.
In addition to button-presses, the connection also passes on movement data. The iPhone's accelerometer and gyroscope feed gravity (in Gs), user acceleration, attitude, and rotation rate to the iPad and Mac game, as part of a new "Motion" profile developers can access.
iOS 8 also changes how the idle timer - which controls when the phone locks after a period of the display going untouched - is handled, automatically keeping the iPhone active when in Controller Forwarding mode.
Finally, there's also a new way of handling digital button presses, with iOS apps now able to track both when the button is pressed and when it is released. That could allow for game actions like pressing down to begin filling a boost bar, and then releasing the button to trigger the boost.
There's more on iOS 8 and everything announced at WWDC 2014 in the SlashGear Apple Hub.