PolyPort

What this tool actually does

PolyPort is a source-level idiom translator. It rewrites the parts of app code that have a mechanical equivalent on another platform: types, method/lifecycle names, collection access, logging, null handling, string interpolation, class inheritance, event listeners and platform-specific calls that it can turn into a flagged placeholder.

Handled automatically

• Types & primitives — int ↔ Int ↔ int, boolean ↔ Bool ↔ bool, String ↔ string, void ↔ Void ↔ Unit.
• Collections — ArrayList<T> ↔ Array<T> ↔ [T] ↔ List<T>, maps, and .add/.append, .size()/.count/.Count, .get(i).
• Lifecycle — onCreate → viewDidLoad → MainWindow ctor, plus super calls.
• Declarations — void foo(Bar b) ↔ fun foo(b: Bar) ↔ func foo(b: Bar), parameter order reformatting included.
• Logging — Log.d / println / print / Console.WriteLine.
• Null & self — null ↔ nil, this ↔ self, ?: ↔ ??.
• Control flow — parenthesised if/while/switch, indexed for loops, break handling, try/catch → do/catch.
• Strings — Swift interpolation "x \(y)" → concatenation (Java/C#) or ${y} (Kotlin).
• Inheritance — extends / implements / : rewritten to the target syntax.

Always needs a human

• UI construction — XML layouts, storyboards, XAML and Compose/SwiftUI are not interchangeable 1:1.
• Anonymous classes / closures that capture state (Java new OnClickListener(), C# lambdas).
• Concurrency primitives (AsyncTask / GCD / Dispatcher), background schedulers, push notifications.
• Storage, billing, permissions, and anything tied to a store or vendor SDK.
• Build files, resources and packaging.

Real cross-platform routes

• One codebase, all three: Flutter, React Native, .NET MAUI, Kotlin Multiplatform (with Compose Multiplatform).
• Android → iOS: rewrite on Apple frameworks, or share logic via Kotlin Multiplatform.
• Windows → mobile: .NET MAUI or Blazor Hybrid keeps the C# layer.