Integrating pointer interactions into your iPad app

At a glance

Project structure

PointerInteraction/
├── ViewController.swift
├── ViewController+PointerInteraction.swift
├── ViewController+ButtonProvider.swift
├── ViewController+ContextMenu.swift
├── ShapeView.swift
├── AlphaControl.swift
├── AppDelegate.swift
├── SceneDelegate.swift
└── Base.lproj/Main.storyboard

Structure observations

• ViewController.swift owns assembly and gestures; three extensions isolate unrelated interaction contracts.
• Shape subclasses share hit testing and preview construction in ShapeView, overriding only path geometry.
• AlphaControl contains its drawing, labels, pan-to-alpha logic, and preview path in one custom control.

Overall architecture

flowchart LR
    Storyboard["Storyboard views"] --> Controller["ViewController"]
    Controller --> Buttons["UIButton pointerStyleProvider"]
    Controller --> Shapes["ShapeView instances"]
    Controller --> Alpha["AlphaControl"]
    Shapes --> Pointer["UIPointerInteraction"]
    Alpha --> Pointer
    Pointer --> Delegate["ViewController pointer extension"]
    Delegate --> Region["UIPointerRegion"]
    Delegate --> Style["UIPointerStyle"]
    Shapes --> Gestures["pan / tap / pinch / hover"]
    Shapes --> Context["UIContextMenuInteraction"]
    Context --> MenuExtension["context-menu extension"]

Reference code

PointerInteraction/ViewController.swift:24 — the controller installs interactions, but asks each custom view for the geometry used by those interactions.

// Set the alpha control's color, and add a pointer interaction.
alphaControl.currentColor = UIColor.systemOrange
alphaControl.addInteraction(UIPointerInteraction(delegate: self))

setupShapeView(shapeView: ovalShape, color: UIColor.systemRed, label: "Lift")
setupShapeView(shapeView: roundRectShape, color: UIColor.systemGreen, label: "Highlight")
setupShapeView(shapeView: triangleShape, color: UIColor.systemGray, label: "Hover")
setupShapeView(shapeView: squareShape, color: UIColor.systemBlue, label: "Automatic")

Interpretation

The controller is the shared UIKit delegate because it coordinates several view types, but it does not duplicate geometry. ShapeView.targetedPreview(), innerPath, and AlphaControl.highlightRegion keep visual knowledge at the view boundary.

Ownership and state

classDiagram
    ViewController o-- ShapeView : storyboard outlets
    ViewController o-- AlphaControl : storyboard outlet
    ShapeView <|-- TriangleShapeView
    ShapeView <|-- RoundrectShapeView
    ShapeView <|-- OvalShapeView
    ShapeView *-- UIBezierPath : outer and inner paths
    ShapeView *-- UILabel : effect label
    AlphaControl *-- UILabel : value and color labels
    AlphaControl *-- UIView : swatch
    ViewController ..|> UIPointerInteractionDelegate
    ViewController ..|> UIContextMenuInteractionDelegate
    ViewController ..|> UIGestureRecognizerDelegate

Ownership evidence

PointerInteraction/ShapeView.swift:10 — the base view owns reusable visual geometry and effect label state that its subclasses specialize.

class ShapeView: UIView {
    // ...
}

Class and protocol design

There is no app-defined protocol. UIKit delegate protocols are applied in capability-specific extensions; subclassing provides the one app-defined polymorphic seam for shape geometry.

Access control

Reference code

PointerInteraction/AlphaControl.swift:12 — semantic state is target-visible for setup, while child views and drawing constants remain private.

var currentColor = UIColor.gray
var currentAlpha: CGFloat = 1.0

static let regionIdentifier: AnyHashable = "colorPath"

private let marginSpacing: CGFloat = 6.0
private let cornerRadius: CGFloat = 12.0

private var colorSwatch: UIView!
private var colorLabel: UILabel!
private var valueLabel: UILabel!

Logic ownership and placement

Design patterns

Naming conventions

• Shape subclasses name geometry directly: TriangleShapeView, RoundrectShapeView, and OvalShapeView.
• Capability files use ViewController+... suffixes that match UIKit features.
• targetedPreview, highlightRegion, and regionIdentifier use pointer/context-menu vocabulary consistently.
• setup..., pan..., tap..., scale..., and hover... distinguish configuration from gesture commands.

Architecture takeaways

• Keep pointer preview paths and hit-testing geometry in the custom view that draws the shape.
• Split one interaction-heavy controller by framework capability when callbacks share the same state owner.
• Use a small override point when visual variants differ only in geometry.
• Expose semantic control state while keeping child views and layout constants private.

Source map

• Official Apple documentation