Using SwiftUI with UIKit

At a glance

Project structure

Source bundle/
├── UseSwiftUIWithUIKit/
│   ├── AppDelegate.swift
│   ├── Examples/
│   │   ├── SwiftUI in Cells/
│   │   │   ├── SwiftUI Views/
│   │   │   │   ├── HeartRateCellView.swift
│   │   │   │   ├── SleepCellView.swift
│   │   │   │   ├── HealthCategoryCellView.swift
│   │   │   │   └── StepCountCellView.swift
│   │   │   └── HostingConfigurationExample.swift
│   │   ├── Data Flow with SwiftUI Cells/
│   │   │   └── CellDataFlowExample.swift
│   │   └── SwiftUI View Controllers/
│   │       └── HostingControllerExample.swift
│   ├── MainMenuViewController.swift
│   └── SceneDelegate.swift
├── Configuration/
│   └── SampleCode.xcconfig
└── UseSwiftUIWithUIKit.xcodeproj/
    └── .xcodesamplecode.plist

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 6 project/configuration file(s) and 33 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["HostingConfigurationViewController"]
    N3["DataStore"]
    N4["UIKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

UseSwiftUIWithUIKit/AppDelegate.swift:10 — architecture anchor

@main
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }

    // MARK: UISceneSession Lifecycle

    func application(
        _ application: UIApplication,
        configurationForConnecting connectingSceneSession: UISceneSession,
        options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        // Called when a new scene session is being created.
        // Use this method to select a configuration to create the new scene with.
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }
}

Interpretation

The arrows summarize the source-visible entry, role-named types or folders, and framework direction; when nodes come from structural folders, the sequence is a high-level interpretation rather than proof that every adjacent node calls the next. Ownership is claimed only where the next section cites a stored property or assignment. The diagram is intentionally limited to the dominant path into UIKit.

Ownership and state

classDiagram
    HeartRateSample *-- UUID : id
    HeartRateSample *-- Date : time
    HeartRateSample *-- Int : beatsPerMinute
    HeartRateCellView o-- HeartRateData : data

Ownership evidence

UseSwiftUIWithUIKit/Examples/SwiftUI in Cells/SwiftUI Views/HeartRateCellView.swift:12 — stored dependency or nearest verified ownership anchor

struct HeartRateSample: Identifiable {
    let id: UUID
    var time: Date
    var beatsPerMinute: Int
}

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

UseSwiftUIWithUIKit/Examples/Data Flow with SwiftUI Cells/CellDataFlowExample.swift:19 — representative execution boundary

@MainActor
private class MedicalCondition: Identifiable, ObservableObject {
    // ...
    let id: UUID
    // ...
}

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

UseSwiftUIWithUIKit/AppDelegate.swift:11 — representative type boundary

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    // ...
        return true
    // ...
}

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

Access control

Reference code

UseSwiftUIWithUIKit/Examples/Data Flow with SwiftUI Cells/CellDataFlowExample.swift:55 — representative boundary

    private var data: (conditions: [MedicalCondition], conditionsByID: [MedicalCondition.ID: MedicalCondition]) = ([], [:]) {
        // ...
            NotificationCenter.default.post(name: .medicalConditionsDidChange, object: nil)
        // ...
    }

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: HostingConfigurationViewController, HostingControllerViewController, MainMenuViewController, MedicalConditionsViewController; Delegate: AppDelegate, SceneDelegate; Store: DataStore; View: HealthCategoryCellView, HeartHealthAlertView, HeartRateBPMView, HeartRateCellView, HeartRateChartView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: application, generateRandomData, getDefaultConditions, medicalCondition, populateDefaultMedicalConditions, addNewMedicalCondition, delete, shuffleMedicalConditions.
• Files: UseSwiftUIWithUIKit/AppDelegate.swift, UseSwiftUIWithUIKit/Examples/SwiftUI in Cells/SwiftUI Views/HeartRateCellView.swift, UseSwiftUIWithUIKit/Examples/SwiftUI in Cells/SwiftUI Views/SleepCellView.swift, UseSwiftUIWithUIKit/Examples/SwiftUI in Cells/SwiftUI Views/HealthCategoryCellView.swift, UseSwiftUIWithUIKit/Examples/SwiftUI in Cells/SwiftUI Views/StepCountCellView.swift, UseSwiftUIWithUIKit/MainMenuViewController.swift.

Architecture takeaways

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