Sample CodeiOS, iPadOS, Mac Catalyst, macOS, visionOSReviewed 2026-07-21View on Apple Developer

Adopting drag and drop using SwiftUI

At a glance

Item Summary
Purpose Enable drag-and-drop interactions in lists, tables and custom views.
App architecture A Swift sample with the source-visible chain AdoptingDragAndDropInASwiftUIAppAppContentViewDataModelSwiftUI APIs.
Main patterns Binding-based state propagation
Project style 12 scanned source file(s) across Swift, organized around ranked entry, type, and file boundaries.

Project structure

Source bundle/
└── AdoptingDragAndDropInASwiftUIApp/
    ├── AdoptingDragAndDropInASwiftUIAppApp.swift
    ├── Models/
    │   ├── DataModel.swift
    │   ├── Constants.swift
    │   └── Contact.swift
    └── Views/
        ├── ContactDetailView.swift
        ├── ContactInfoView.swift
        ├── HeaderView.swift
        ├── ContentView.swift
        ├── ThumbnailView.swift
        ├── ContactsTable.swift
        ├── ContactList.swift
        └── DisplayModePicker.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 5 project/configuration file(s) and 18 source declaration(s).

Overall architecture

Reference code

AdoptingDragAndDropInASwiftUIApp/AdoptingDragAndDropInASwiftUIAppApp.swift:10 — architecture anchor

@main
struct AdoptingDragAndDropInASwiftUIApp: App {
    // ...
}

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 SwiftUI.

Ownership and state

Ownership evidence

AdoptingDragAndDropInASwiftUIApp/AdoptingDragAndDropInASwiftUIAppApp.swift:12 — stored dependency or nearest verified ownership anchor

    @State private var dataModel = DataModel()
Owner Object or state Relationship Mutation authority
AdoptingDragAndDropInASwiftUIApp DataModel (dataModel) owns wrapper-managed state Owning lexical scope
DataModel Array (contacts) owns value state App/module collaborators
DataModel DisplayMode (displayMode) stores or receives App/module collaborators
Video URL (url) owns value state App/module collaborators

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.

Class and protocol design

AdoptingDragAndDropInASwiftUIApp/AdoptingDragAndDropInASwiftUIAppApp.swift:11 — representative type boundary

struct AdoptingDragAndDropInASwiftUIApp: App {
    // ...
}
Type Responsibility Depends on or conforms to
AdoptingDragAndDropInASwiftUIApp Application entry and top-level composition App
DataModel Feature data or observable state Concrete collaborators/imported frameworks
ContactDetailView User-interface presentation and input forwarding View
ContactInfoView User-interface presentation and input forwarding View
HeaderView User-interface presentation and input forwarding View
VideoView User-interface presentation and input forwarding View
ContentView User-interface presentation and input forwarding View
ThumbnailView User-interface presentation and input forwarding View
CompactContactView User-interface presentation and input forwarding View
VideoLabelView User-interface presentation and input forwarding View

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

Access control

Symbol Access Verified effect Likely rationale
dataModel (AdoptingDragAndDropInASwiftUIApp/AdoptingDragAndDropInASwiftUIAppApp.swift:12) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.
dataModel (AdoptingDragAndDropInASwiftUIApp/Views/ContactList.swift:13) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.
isTargeted (AdoptingDragAndDropInASwiftUIApp/Views/ContactList.swift:14) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.
horizontalSizeClass (AdoptingDragAndDropInASwiftUIApp/Views/ContactsTable.swift:12) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.

Reference code

AdoptingDragAndDropInASwiftUIApp/AdoptingDragAndDropInASwiftUIAppApp.swift:12 — representative boundary

    @State private var dataModel = DataModel()

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

Logic Owning type or file Placement rationale
Application entry and top-level composition AdoptingDragAndDropInASwiftUIApp The source’s App suffix makes this role explicit.
Feature data or observable state DataModel The source’s Model suffix makes this role explicit.
User-interface presentation and input forwarding CompactContactView, ContactDetailView, ContactInfoView, ContentView The source’s View suffix makes this role explicit.

Design patterns

Pattern Source evidence Purpose or tradeoff
Binding-based state propagation AdoptingDragAndDropInASwiftUIApp/Views/DisplayModePicker.swift:11 A binding exposes controlled read/write access while the upstream owner remains authoritative.

Naming conventions

  • Types: App: AdoptingDragAndDropInASwiftUIApp; Model: DataModel; View: CompactContactView, ContactDetailView, ContactInfoView, ContentView, HeaderView.
  • Protocols: no local protocol declaration in the scanned source.
  • Methods: handleDroppedContacts, loadImage, loadItem, copyLibraryFile, makeBody.
  • Files: AdoptingDragAndDropInASwiftUIApp/Models/DataModel.swift, AdoptingDragAndDropInASwiftUIApp/Views/ContactDetailView.swift, AdoptingDragAndDropInASwiftUIApp/Views/ContactInfoView.swift, AdoptingDragAndDropInASwiftUIApp/Views/HeaderView.swift, AdoptingDragAndDropInASwiftUIApp/Views/ContentView.swift, AdoptingDragAndDropInASwiftUIApp/Views/ThumbnailView.swift.

Architecture takeaways

  • AdoptingDragAndDropInASwiftUIAppApp is the main source-visible entry or composition anchor for this sample.
  • Framework work reaches SwiftUI, Contacts, PhotosUI, UniformTypeIdentifiers 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

Source file Relevant symbols
AdoptingDragAndDropInASwiftUIApp/AdoptingDragAndDropInASwiftUIAppApp.swift AdoptingDragAndDropInASwiftUIApp
AdoptingDragAndDropInASwiftUIApp/Models/DataModel.swift DataModel, Video
AdoptingDragAndDropInASwiftUIApp/Views/ContactDetailView.swift ContactDetailView, DisplayMode
AdoptingDragAndDropInASwiftUIApp/Views/ContactInfoView.swift ContactInfoView, ContactDetailLabelStyle
AdoptingDragAndDropInASwiftUIApp/Views/HeaderView.swift HeaderView, VideoView
AdoptingDragAndDropInASwiftUIApp/Views/ContentView.swift ContentView
AdoptingDragAndDropInASwiftUIApp/Views/ThumbnailView.swift ThumbnailView
AdoptingDragAndDropInASwiftUIApp/Views/ContactsTable.swift ContactTable, CompactContactView, VideoLabelView
AdoptingDragAndDropInASwiftUIApp/Models/Constants.swift Constants
AdoptingDragAndDropInASwiftUIApp/Models/Contact.swift Contact