4. Competition and the 99¢ Problem

8. User Interface Fundamentals Threading/Timers Memory Management AuthenticationCryptography Devices GeolocationSensorsNFC SVGTilesTouch eventsAccessibilityPrinting HTML5/CSSXAMLOpen GLControlsData Binding Communications & Data XMLNetworkingSMSNotifications StreamsContractsLocal & Cloud Storage Media PlaybackCaptureAir PlayVisual Effects

14. Press and hold to learnTap for primary actionSlide to drag Swipe to select Pinch to zoom Swipe from edge for app commands Rotate to rotate Swipe from edge for system commands

18. Snapped Filled LandscapePortrait