Sefism.Mobile development: Flutter

Tauseef Fayyaz

A to Z

Glossary

Every concept in this sheet, plus the smaller terms it uses. Select a concept to open its card.

Classes and immutable models: Dart classes have fields, constructors with named and required parameters, and factory constructors.
Constraints go down, sizes go up: A parent passes size limits (constraints) to each child, the child picks a size within them, and the parent positions it.

Declarative UI: You describe what the screen should look like for the current state, and the framework works out what to change on screen.

Futures, async and await: A Future is a value that arrives later, such as an HTTP response.

Hot reload and previews: Tools that show code changes in a running app or an editor preview within a second or two, without rebuilding the whole app.

Isolates: Dart runs your code on one thread per isolate, and isolates share no memory.

Lazy lists: A lazy list only builds the rows currently on screen, plus a few ahead, and recycles them as you scroll.
List, Map and Set: The core collections: ordered List, key-value Map and unique Set.

Packages and pubspec.yaml: pubspec.yaml lists your app's dependencies, assets and SDK constraints.
Platform design guidelines: Material Design 3 is Google's design system for Android, and the Human Interface Guidelines are Apple's rules for iOS.

Rows, columns and stacks: The basic layout containers place children horizontally, vertically or on top of each other, with spacing and alignment options.

Safe areas and screen sizes: Safe areas, or insets, are the parts of the screen not covered by the notch, status bar, camera cutout or gesture bar.
Sealed classes, records and patterns: Dart 3 adds sealed class families, records such as (int, String) and patterns that destructure values.
Sound null safety: A type like String can never hold null; only String? can.
Streams: A Stream delivers many values over time, like location updates or database changes.

Text input and forms: A text field shows a value from state and reports every change back.
Theming and dark mode: A theme defines colours, typography and shapes in one place.

var, final and const: var can be reassigned, final is set once at runtime, and const is a compile-time constant that is created once and shared.

Widgets, elements and BuildContext: A widget is an immutable description of part of the UI.