Chapter 14. Game Controllers and External Screens
iOS devices can interact with a wide range of other devices. Some of these devices, such as external screens and game controllers, are particularly useful when you’re building games!
iOS has supported multiple screens for several versions now, but as of iOS 7 it also supports game controllers, which are handheld devices that provide physical buttons for your players to use. Game controllers have both advantages and disadvantages when compared with touchscreens. Because a game controller has physical buttons, the player’s hands can feel where the controls are, which makes it a lot easier to keep attention focused on the action in the game. Additionally, game controllers can have analog inputs: a controller can measure how hard a button is being held down, and the game can respond accordingly. However, game controllers have fixed buttons that can’t change their position, or look and feel, which means that you can’t change your controls on the fly.
Game controllers that work with iOS devices must obey a set of design constraints specified by Apple; these constraints mean that you can rely on game controllers built by different manufacturers to all behave in a consistent way and provide the same set of controls for your games. In a move that is both as empowering for gamers as it is infuriating for developers, Apple requires that all iOS games must be playable without a controller at all, even if they support a controller. A controller ...