onPencilSqueeze(perform:)

Adds an action to perform when the user squeezes their Apple Pencil.

Declaration

nonisolated func onPencilSqueeze(perform action: @escaping (PencilSqueezeGesturePhase) -> Void) -> some View

Parameters

action:
The action to perform when the user squeezes their Apple Pencil.

Return Value

A view that performs action when the user squeezes their Apple Pencil.

Discussion

You should respect people’s setting for the squeeze gesture by reading the preferredPencilSqueezeAction environment value, if the setting makes sense in your app. If it doesn’t, consider giving people a way to specify custom behavior in your app instead.

In the example below, completing an Apple Pencil squeeze gesture will…

do nothing if this is what the user selected in the Settings app,
switch the tool to ”Lasso” if this is the action they have configured in the app,
spill the ink if this is the action they have configured in the app,
present a custom contextual palette if they haven’t configured a custom action in the app and this is what they selected in the Settings app.

enum MyPencilAction: String {
    case spillInk
    ...
}

@Environment(\.preferredPencilSqueezeAction) private var preferredAction
@AppStorage("customPencilSqueezeAction") private var customAction: MyPencilAction?

@State private var contextualPaletteAnchor: PopoverAttachmentAnchor?
@State private var contextualPalettePresented = false

var body: some View {
    MyDrawingCanvas()
        .onPencilSqueeze { phase in
            guard preferredAction != .ignore else {
                // Skip if this is what the user prefers.
                return
            }
            if let customAction {
                // If a custom action is configured, respect it.
                if customAction == .spillInk {
                    switch phase {
                        // Spill the ink while the user is squeezing their Apple Pencil.
                    }
                }
            } else if preferredAction == .showContextualPalette, case let .ended(value) = phase {
                // Present a custom contextual palette if the user prefers it.
                contextualPaletteAnchor = value.hoverPose?.anchor.map { .point($0) }
                contextualPalettePresented = true
            }
        }
        .popover(
            isPresented: $contextualPalettePresented,
            attachmentAnchor: contextualPaletteAnchor ?? .point(.center)
        ) {
            MyContextualPalette()
        }