Running macOS in a virtual machine on Apple silicon

At a glance

Project structure

Source bundle/
├── Swift/
│   ├── macOSVirtualMachineSampleApp/
│   │   └── AppDelegate.swift
│   ├── InstallationTool/
│   │   └── main.swift
│   └── Common/
│       └── MacOSVirtualMachineDelegate.swift
└── Objective-C/
    ├── InstallationTool/
    │   ├── main.m
    │   └── MacOSRestoreImage.h
    ├── macOSVirtualMachineSampleApp/
    │   ├── main.m
    │   ├── AppDelegate.h
    │   └── AppDelegate.m
    └── Common/
        ├── MacOSVirtualMachineDelegate.h
        ├── MacOSVirtualMachineDelegate.m
        ├── MacOSVirtualMachineConfigurationHelper.h
        └── MacOSVirtualMachineConfigurationHelper.m

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C/Objective-C header, Objective-C, Swift.
• The verified tree contains 9 project/configuration file(s) and 10 source declaration(s).

Overall architecture

flowchart LR
    Bundle["Sample bundle"]
    V1["Objective-C"]
    V2["Swift"]
    Boundary["Virtualization APIs"]
    Bundle --> V1
    V1 --> Boundary
    Bundle --> V2
    V2 --> Boundary

Reference code

Swift/macOSVirtualMachineSampleApp/AppDelegate.swift:12 — architecture anchor

@main
class AppDelegate: NSObject, NSApplicationDelegate {
    // ...
    @IBOutlet var window: NSWindow!
    // ...
}

Interpretation

The branches represent separate entry-bearing project variants in the downloaded bundle, not runtime calls between those variants. Each branch is intentionally collapsed at the documented framework boundary; the detailed target-local flow remains in the cited files. Ownership is claimed only where the next section cites a stored property or assignment.

Ownership and state

classDiagram
    AppDelegate o-- NSWindow : window
    AppDelegate o-- VZVirtualMachineView : virtualMachineView
    AppDelegate o-- MacOSVirtualMachineDelegate : virtualMachineResponder
    AppDelegate o-- VZVirtualMachine : virtualMachine

Ownership evidence

Swift/macOSVirtualMachineSampleApp/AppDelegate.swift:15 — stored dependency or nearest verified ownership anchor

@main
class AppDelegate: NSObject, NSApplicationDelegate {
    // ...
    @IBOutlet var window: NSWindow!
    // ...
}

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Concurrency, scheduling, and thread safety

Evidence limit: actor isolation, async/await, or Task creation does not by itself prove background-thread execution; Sendable conformance alone does not prove thread-safe mutation.

@MainActor/MainActor.run, DispatchQueue.main, and RunLoop.main are reported as distinct isolation, queue, and event-loop mechanisms. A plain Task is kept separate from Task.detached; neither is labeled as a background thread.

Reference code

Swift/InstallationTool/MacOSVirtualMachineInstaller.swift:49 — representative execution boundary

#if arch(arm64)
        DispatchQueue.main.async { [self] in
            setupVirtualMachine(macOSConfiguration: macOSConfiguration)
            startInstallation(restoreImageURL: restoreImage.url)
        }
#endif

State propagation, frameworks, and dependencies

Evidence limit: an import proves a source-level compilation dependency at the cited line; it does not prove runtime use, architectural adoption, or whether a Swift package is a direct application dependency.

receive(on:) describes downstream delivery scheduling, while subscribe(on:) describes upstream subscription/request/cancel scheduling. An import Combine alone establishes neither behavior nor a Store, reducer, Redux, or other application architecture.

Class and protocol design

Swift/macOSVirtualMachineSampleApp/AppDelegate.swift:13 — representative type boundary

@main
class AppDelegate: NSObject, NSApplicationDelegate {
    // ...
    @IBOutlet var window: NSWindow!
    // ...
}

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Reference code

Objective-C/macOSVirtualMachineSampleApp/AppDelegate.m:19 — representative boundary

@interface AppDelegate ()
// ...
@property (weak) IBOutlet VZVirtualMachineView *virtualMachineView;
// ...
@end

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Design patterns

Main application flow

sequenceDiagram
    participant MacOSRestoreImage
    participant VZMacOSRestoreImage
    participant NSString
    participant NSURLSession
    participant NSFileManager
    participant downloadTaskprogress
    participant downloadTask
    MacOSRestoreImage->>VZMacOSRestoreImage: fetchLatestSupportedWithCompletionHandler()
    MacOSRestoreImage->>NSString: stringWithFormat()
    MacOSRestoreImage->>NSURLSession: downloadTaskWithURL()
    MacOSRestoreImage->>NSString: stringWithFormat()
    MacOSRestoreImage->>NSFileManager: moveItemAtURL()
    MacOSRestoreImage->>downloadTaskprogress: addObserver()
    MacOSRestoreImage->>downloadTask: resume()

Reference code

Objective-C/InstallationTool/MacOSRestoreImage.m:32 — download()

- (void)download:(void (^)(void))completionHandler
{
    [VZMacOSRestoreImage fetchLatestSupportedWithCompletionHandler:^(VZMacOSRestoreImage *restoreImage, NSError *error) {
        if (error) {
            abortWithErrorMessage([NSString stringWithFormat:@"Failed to fetch latest supported restore image catalog. %@", error.localizedDescription]);
        }

        NSLog(@"Attempting to download the latest available restore image.");
        NSURLSessionDownloadTask *downloadTask = [[NSURLSession sharedSession] downloadTaskWithURL:restoreImage.URL
                                                                                 completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
            if (error) {
                abortWithErrorMessage([NSString stringWithFormat:@"Failed to download restore image. %@", error.localizedDescription]);
            }

            if (![[NSFileManager defaultManager] moveItemAtURL:location toURL:getRestoreImageURL() error:&error]) {
                abortWithErrorMessage(error.localizedDescription);
            }

            completionHandler();
        }];

        [downloadTask.progress addObserver:self forKeyPath:@"fractionCompleted" options:NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionNew context:nil];
        [downloadTask resume];
    }];
}

Naming conventions

• Types: Delegate: AppDelegate, MacOSVirtualMachineDelegate.
• Protocols: no local protocol declaration in the scanned source.
• Methods: createMacPlaform, createVirtualMachine, startVirtualMachine, resumeVirtualMachine, restoreVirtualMachine, applicationDidFinishLaunching, applicationShouldTerminateAfterLastWindowClosed, saveVirtualMachine.
• Files: Swift/macOSVirtualMachineSampleApp/AppDelegate.swift, Objective-C/macOSVirtualMachineSampleApp/AppDelegate.h, Objective-C/macOSVirtualMachineSampleApp/AppDelegate.m, Objective-C/Common/MacOSVirtualMachineDelegate.h, Objective-C/Common/MacOSVirtualMachineDelegate.m, Swift/Common/MacOSVirtualMachineDelegate.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches Virtualization, Cocoa, AppKit, sys through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
• Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
• Access-control conclusions separate verified language visibility from the likely design rationale.
• The source does not justify labeling the design protocol-oriented.

Source map

• Official Apple documentation