Allowing the user to control an app through Buttons, Toggles, or Menus is handy, but all of these controls take up space on the screen. To eliminate the need for extra objects on the user interface, your app can also detect and respond to touch gestures that allow direct manipulation of items displayed on the screen.
The different types of touch gestures that an iOS app can detect and respond to include
Tap – A fingertip touches the screen and lifts up.
Pinch – Two fingertips come together or move apart.
Rotation – ...
