Writing Custom Platform Plugins for iOS and Android

Dart cannot call native iOS or Android APIs directly. A platform plugin bridges that gap, exposing Swift/Objective-C and Kotlin/Java capabilities to your Dart code through a typed channel.

• Package: pure Dart, no native code.
• Plugin: Dart API plus platform-specific native implementations.

You write a plugin whenever you need hardware (sensors, BLE), OS services (notifications, keychain), or a native SDK that has no Dart equivalent. In this lesson we author a federated plugin that surfaces native Kotlin and Swift APIs to Dart.

A federated plugin splits responsibilities across several packages so different parties can own different platforms:

• app-facing package (battery): the public Dart API developers import.
• platform interface (battery_platform_interface): an abstract contract all implementations must satisfy.
• platform packages (battery_android, battery_ios): concrete native implementations registered via pubspec.yaml.

This decoupling lets a third party add, say, a Windows implementation without touching the app-facing package. The interface package is the linchpin contract.