zstandard_ios

The iOS implementation of the zstandard Flutter plugin. Uses FFI and the native Zstandard C library.

Installation

Add the main plugin to your app; this package is included automatically via the federated plugin:

dependencies:
  zstandard: ^1.5.0

No extra setup is required for normal use.

Usage

Use the main zstandard API; the iOS implementation is selected automatically on iOS:

import 'package:zstandard/zstandard.dart';

void main() async {
  final zstandard = Zstandard();
  final data = Uint8List.fromList([1, 2, 3, 4, 5]);

  final compressed = await zstandard.compress(data, 3);
  final decompressed = await zstandard.decompress(compressed ?? Uint8List(0));
}

Or use the extension methods:

final compressed = await data.compress(compressionLevel: 3);
final decompressed = await compressed?.decompress();

API

• ZstandardIOS() — Creates the iOS platform implementation.
• compress(Uint8List data, int compressionLevel) — Compresses data (level 1–22). Returns compressed bytes or null.
• decompressWithOptions(Uint8List data, {int maxOutputSize}) — Decompresses complete, concatenated, or unknown-size zstd frames with a bounded output (256 MiB by default). Invalid, truncated, or oversized input returns null.
• getPlatformVersion() — Returns a platform identifier string.

Architecture

This package uses Dart FFI with the native zstd C library. Swift Package Manager statically links the shared target into the app; CocoaPods remains supported and embeds the plugin framework. Both paths compile the same common/compress/decompress source set from zstandard_native. Public work runs in an isolate using Dart-owned bytes and bounded streaming decompression.

Testing

From the package directory:

flutter test

Unit tests run only on iOS (skipped on other platforms). For integration tests, run the main zstandard example app on an iOS device or simulator.

Troubleshooting

• Symbol or framework not found: Ensure the iOS target is built (e.g. flutter run -d ios) and that you are targeting a supported architecture (arm64 device, x86_64/arm64 simulator). SwiftPM loads the statically linked symbols from the process; CocoaPods loads the embedded framework.
• Swift Package Manager: Flutter 3.44 and newer enables this path by default.
• CocoaPods: For older Flutter projects or explicit compatibility testing, run flutter config --no-enable-swift-package-manager and then pod install in your app’s ios/ directory if needed.

See the documentation for more.