Creating a Metal dynamic library

At a glance

Project structure

Source bundle/
├── Renderer/
│   ├── AAPLRenderer.m
│   ├── AAPLShaders.metal
│   └── AAPLShaderTypes.h
└── Application/
    ├── AAPLRenderViewController.m
    ├── main.m
    ├── iOS/
    │   └── AAPLSplitViewController.m
    ├── WindowSceneDelegate.m
    ├── AAPLAppDelegate.h
    └── AAPLAppDelegate.m

Structure observations

• The entry/composition boundary and renderer or operation boundary are separate in the source; AAPLRenderer is the principal feature coordinator.
• GPU-specific logic stays in Metal shader files; shared headers bridge host/shader layouts where present.
• The tree above is intentionally pruned to composition, resource, and shader files.

Overall architecture

flowchart LR
    N1["AAPLEditViewController"]
    N2["AAPLRenderer"]
    N3["runtime Metal library linking"]
    N4["functions loaded from a dynamic library"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

Renderer/AAPLRenderer.m:515 — feature handoff or setup anchor

    id<MTLDynamicLibrary> dynamicLib = [_device newDynamicLibrary:lib
                                                            error:&error];
    if(!dynamicLib && error)
    {
        NSLog(@"Error creating dynamic library from source library: %@", error);
        return;
    }

Interpretation

This is the dominant control/data path: platform code composes AAPLRenderer; that object controls runtime Metal library linking; GPU-visible work ends in functions loaded from a dynamic library. The arrows summarize responsibility transfer, not a claim that every node directly calls the next.

Ownership and state

classDiagram
    AAPLRenderViewController *-- AAPLRenderer : _renderer

Ownership evidence

Application/AAPLRenderViewController.m:50 — AAPLRenderViewController creates and stores _renderer

@implementation AAPLRenderViewController
// ...
    _renderer = [[AAPLRenderer alloc] initWithMetalKitView:_view];
// ...
@end

Class and protocol design

Framework delegate conformance is a callback seam; the source does not justify calling the whole app protocol-oriented.

Access control

This sample does not use Swift private, fileprivate, or public for its native boundary. Objective-C/Objective-C++ use header versus implementation placement, C++ uses access specifiers/linkage, Python uses module conventions, and Metal entry points cross a compiled-library boundary; these are not Swift access levels.

Logic ownership and placement

Shader boundary reference

Renderer/AAPLUserDylib.metal:12 — default dynamically linked function implementation

float4 AAPLUserDylib::getFullScreenColor(float4 inColor)
{
    return float4(inColor.r, inColor.g, inColor.b, 0);
}

Design patterns

Naming conventions

• Role suffixes make ownership visible: AAPLEditViewController, AAPLRenderViewController, AAPLSplitViewController, AAPLRenderer, AAPLAppDelegate, WindowSceneDelegate.
• Method names describe setup or encoding actions: application, applicationShouldTerminateAfterLastWindowClosed, viewDidLoad, onClick, registerForKeyboardNotifications, keyboardWasShown, keyboardWillBeHidden.
• Shader entry points use stage/operation names: vertexShader, fragmentShader, dylibKernel.
• AAPL is a sample namespace prefix, not a recommendation for production module naming; retain semantic suffixes such as Renderer, Manager, Scene, or Adapter.

Architecture takeaways

• Keep AAPLEditViewController focused on composition; AAPLRenderer is the owner of runtime Metal library linking.
• Treat functions loaded from a dynamic library as a separate execution/compilation boundary with explicit resource and data-layout contracts.
• The verified ownership edge is AAPLRenderViewController → _renderer; broader exclusive ownership is not inferred.
• Access-control rationale follows concrete language boundaries rather than translating every header or shader symbol into Swift terms.

Source map

• Official Apple documentation