Platform adapters

Nutrient Flutter SDK includes platform adapters as a built-in extensibility mechanism. They give you direct access to the native Nutrient PDF SDKs on each platform, enabling advanced customization beyond what the cross-platform API exposes.

What are platform adapters?

Platform adapters are an extension point in Nutrient Flutter SDK that use native language bindings to communicate with the underlying Nutrient PDF SDKs:

• Android — JNI bindings via the jni package for direct Java/Kotlin interop.
• iOS — Objective-C bindings via the objective_c package for direct Swift/Objective-C interop.
• Web — JavaScript interop via dart:js_interop for direct access to Nutrient Web SDK.

Pass an adapter to NutrientView for capabilities beyond the standard PdfConfiguration options — such as listening to native lifecycle events, customizing platform-specific UI elements, or calling native SDK methods directly.

When to use platform adapters

Platform adapters are appropriate for the following use cases:

1. Advanced UI customization
   • Custom toolbar configurations
   • Platform-specific menu items
   • Contextual toolbar modifications
2. Full event access
   • Native document lifecycle events
   • Annotation change callbacks
   • Page rendering events
3. Platform-specific features
   • Features only available on one platform
   • Deep integration with native APIs
   • Custom rendering or processing
4. Direct platform SDK access
   • Direct calls via JNI (Android), FFI (iOS), or JS interop (Web)
   • Fine-grained control over SDK behavior

Architecture

Platform adapters follow a layered architecture within Nutrient Flutter SDK, outlined in the image below.

Key components

1. NutrientView — Flutter widget for displaying PDF documents; accepts an optional adapter parameter
2. Nutrient — SDK initialization and license configuration
3. NutrientController — Base controller class for document interaction
4. Platform adapters — Customizable bridges to native SDK functionality

The adapter pattern

Platform adapters are the core extension point. Each adapter:

• Extends a base adapter class (AndroidAdapter, IOSAdapter, or NutrientWebAdapter)
• Receives lifecycle callbacks for customization
• Implements custom controller interfaces
• Has full access to native SDK APIs

Package structure

Nutrient Flutter SDK is composed of several packages:

Next steps

• Getting started — Installation and setup
• Usage patterns — Examples and patterns
• Platform imports — Handling platform-specific imports