# appkit Typed Cocoa / AppKit bindings for building native macOS desktop apps. The package is one generated module — the canonical entry point is `import "appkit/appkit" as appkit;` — produced by `cpc-bindgen` from the AppKit SDK headers, so it tracks the framework class-for-class: hundreds of Cocoa classes (`Application`, `Window`, `View`, `Button`, `TextField`, `Menu`, `Toolbar`, and the rest) each surface as a typed `{ _obj }` wrapper carrying `raw()` and `from_raw()`. Callbacks are closure-free, in keeping with C+ having no closures. Action controls use Cocoa's target/action: a factory like `Button::button_with_title(title, target, action)` takes a target object and an action selector, and block-taking APIs accept a named `fn(...)` pointer plus a `ctx: *u8` (for example `DraggingItem::set_image_components_provider(cb, ctx)`). Data crosses the boundary through `objc/bridge`: a `str` coerces to `NSString`, methods hand back `Text`, arrays arrive as `Vec[T]`, and `NSData` is the `Data` wrapper; the geometry structs `rt::Point`, `rt::Size`, and `rt::Rect` cross verbatim. ## Ownership: the "+1 normal form" Types the generator recognizes as `alloc`/`init`-owned carry a `drop(ref this)` that releases their Objective-C object exactly once — `Window`, `View`, `Menu`, `Toolbar`, and the owned Foundation values (`AttributedString`, `Data`, and friends) all follow this one rule, so a wrapper that goes out of scope cannot leak. Objects handed back from autoreleasing factory methods (`Button::button_with_title`, `TextField::label_with_string`) or shared accessors (`Application::shared_application`) are non-owning wrappers with no `drop`, and are never released. Over 150 types carry the owning `drop`. ## Drag and drop AppKit supports both ends of a drag. A drop **destination** registers for dropped data, and a drag **source** can begin a drag from a `mouseDragged:` gesture by building `DraggingItem`s (`DraggingItem::new` / `DraggingItem::new_with_pasteboard_writer`) and calling `View::begin_dragging_session_with_items(items, event, source)`, which returns a `DraggingSession`. A runnable `appkit_drag_drop` recipe lives in the compiler repo. ## Labels vs. fields `TextField::label_with_string` is a true static label — non-editable and non-bezeled — so it does not behave like an input or accept dropped text. Use `TextField::text_field_with_string` (or the `TextField` initializers) when you want an editable field. ```cplus import "appkit/appkit" as appkit; fn main() -> i32 { let app = appkit::Application::shared_application(); app.set_activation_policy(appkit::ApplicationActivationPolicy::Regular); // ... build window + controls ... app.run(); return 0; } ``` ## Parenting, symbols, and widgets Every wrapper exposes `raw()` to hand its Objective-C pointer to a parent that will own it and `from_raw()` to re-wrap one, so a view moved into a parent is not double-released. The bindings also cover **SF Symbols** — `Image::image_with_system_symbol_name(name, description)` returns `Option[Image]` — layer-backed views via `View::set_wants_layer`, and broad toolbar and text coverage. A runnable reference app lives in the compiler repo at `docs/examples/recipes/appkit_hello/`; the public walkthrough is [AppKit hello](/examples/appkit-hello). For the underlying Objective-C message-send mechanics, see [FFI](/docs/ffi). To drive an AppKit app from an external agent, see the [agent surface](/docs/agent-surface) and [agent_appkit](/docs/packages/agent_appkit).