Introduction

• UI framework created by Google.
• One codebase for:
  • Android apps
  • iOS apps
  • Web apps
  • Desktop apps
• Write in Dart.

  • Has sound null safety.

    
    // cannot be null
    String name = "Min Hen";     
    // nullable
    String? nickname;         
    
    // Safe access:
    print(nickname?.length);
    // Force:
    nickname!.length
    

  • Futures (Async)

    • Flutter UI must never block the main thread.

    Future<String> fetchUser() async {
      await Future.delayed(Duration(seconds: 2));
      return "User";
    }
    

  • Use Isolates (communicate via message passing)

    • Dart does not use shared-memory threads.

    Main Isolate (UI)
         |
         | message passing
         |
    Worker Isolate
    

Compilation

JIT (Development)

• Allows Hot Reload.

Dart Code
   ↓
JIT Compiler
   ↓
Machine Code (runtime)

AOT (Production)

• Makes Flutter fast as native apps.
• Smaller runtime overhead

Dart Code
   ↓
AOT Compiler
   ↓
Native ARM / x64 code

Widget