Implementing modern collection views

At a glance

Project structure

Source bundle/
├── Modern Collection Views/
│   ├── Compositional Layout/
│   │   ├── Controllers/
│   │   │   ├── ConferenceVideoController.swift
│   │   │   └── ConferenceNewsController.swift
│   │   └── Basics View Controllers/
│   │       └── ItemBadgeSupplementaryViewController.swift
│   ├── Lists/
│   │   └── CustomCellListViewController.swift
│   ├── OutlineViewController.swift
│   ├── Cell Configurations/
│   │   └── CustomConfigurationViewController.swift
│   ├── Diffable/
│   │   ├── WiFiSettingsViewController.swift
│   │   └── TableViewEditingViewController.swift
│   └── AppDelegate.swift
└── Modern Collection Views Mac/
    ├── Compositional Layout/
    │   └── Basics Window Controllers/
    │       └── ItemBadgeSupplementaryWindowController.swift
    ├── Diffable/
    │   └── WiFiSettingsWindowController.swift
    └── AppDelegate.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: Swift.
• The verified tree contains 29 project/configuration file(s) and 123 source declaration(s).

Overall architecture

flowchart LR
    Bundle["Sample bundle"]
    V1["Modern Collection Views Mac"]
    V2["Modern Collection Views"]
    Boundary["UIKit APIs"]
    Bundle --> V1
    V1 --> Boundary
    Bundle --> V2
    V2 --> Boundary

Reference code

Modern Collection Views Mac/AppDelegate.swift:10 — architecture anchor

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
    // ...
    private var listWindowController = ListWindowController(windowNibName: "ListWindow")
    // ...
}

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
    ItemBadgeSupplementaryWindowController *-- NSUserInterfaceItemIdentifier : badgeSupplementaryViewReuseIdentifier
    Model *-- String : title
    Model *-- Int : badgeCount
    Model *-- UUID : identifier

Ownership evidence

Modern Collection Views Mac/Compositional Layout/Basics Window Controllers/ItemBadgeSupplementaryWindowController.swift:13 — stored dependency or nearest verified ownership anchor

class ItemBadgeSupplementaryWindowController: NSWindowController {
    // ...
    static let badgeSupplementaryViewReuseIdentifier = NSUserInterfaceItemIdentifier("contact-badge-reuse-identifier")
    // ...
}

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

Modern Collection Views Mac/Diffable/InsertionSortWindowController.swift:82 — representative execution boundary

        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(delay)) {
            if shouldReset {
                let randomizedSnapshot = self.snapshot(for: bounds)
                self.dataSource.apply(randomizedSnapshot, animatingDifferences: false)
            }
            self.performSortStep()
        }

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

Modern Collection Views Mac/AppDelegate.swift:11 — representative type boundary

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
    // ...
    private var listWindowController = ListWindowController(windowNibName: "ListWindow")
    // ...
}

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

Access control

Reference code

Modern Collection Views Mac/AppDelegate.swift:13 — representative boundary

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
    // ...
    private var listWindowController = ListWindowController(windowNibName: "ListWindow")
    // ...
}

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

Naming conventions

• Types: Controller: AdaptiveSectionsViewController, AdaptiveSectionsWindowController, ConferenceNewsController, ConferenceNewsFeedViewController, ConferenceVideoController; DataSource: DataSource; Delegate: AppDelegate; Model: Model; View: BadgeSupplementaryView, BadgeView, CustomContentView, SectionBackgroundDecorationView, TitleSupplementaryView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: hash, generateCollections, viewDidLoad, createLayout, configureHierarchy, configureDataSource, collectionView, updateWithItem.
• Files: Modern Collection Views/Compositional Layout/Controllers/ConferenceVideoController.swift, Modern Collection Views/Lists/CustomCellListViewController.swift, Modern Collection Views/OutlineViewController.swift, Modern Collection Views Mac/Compositional Layout/Basics Window Controllers/ItemBadgeSupplementaryWindowController.swift, Modern Collection Views Mac/Diffable/WiFiSettingsWindowController.swift, Modern Collection Views/Cell Configurations/CustomConfigurationViewController.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches UIKit, Cocoa 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