Components and styling.
WHAT THE CORE COMPONENTS ARE
A generic container Text, which must wrap all text Images Scrollable containers Efficient list components Touchable elements
WHY TEXT MUST BE WRAPPED
Unlike the web, text cannot sit directly in a container.
WHAT STYLING USES
A subset of styling similar to the web, defined in JavaScript objects.
WHAT DIFFERS FROM THE WEB
No cascade or inheritance, except for some text properties Layout uses flexbox by default Units are density-independent, without a unit suffix
WHAT THAT MEANS
Styles apply only where declared, which is more predictable and more verbose.
WHAT TO USE FOR LONG LISTS
The virtualised list components, never a scroll view containing everything.
WHY
A scroll view renders every child, which exhausts memory.
WHAT TO PROVIDE FOR LISTS
A stable key for each item An item layout hint, where item size is known
WHY THAT SECOND POINT
It removes measurement work and improves scrolling substantially.
WHAT TO HANDLE
Platform differences in shadows, elevation and fonts.
WHAT TO TEST
Both platforms, physically, at several screen sizes.
