Post

Replies

Boosts

Views

Activity

Finger input interrupted while drawing with Apple Pencil + palm resting on display
I’m investigating an issue with simultaneous Apple Pencil and finger input on iPad. Apple Pencil + finger input works correctly while the Pencil user’s hand/palm is off the display. However, when drawing naturally with Apple Pencil with the palm resting on the display, an existing finger drawing contact elsewhere on the screen can be cancelled and then stop receiving input for several seconds. Pencil input continues normally throughout. Initially I suspected PencilKit, but I’ve reproduced the underlying behaviour below PencilKit/SwiftUI. Instrumenting UIKit at UIApplication.sendEvent shows the finger touch being cancelled and, in some cases, no further events for that finger for ~4–5 seconds while Pencil MOVED events continue to arrive normally. Everything delivered to the application is accounted for, so this appears to occur before our drawing/rendering code. Is this expected behaviour from the iPad’s Pencil/palm rejection? More specifically: Is there any supported way to tell UIKit that an existing finger contact should remain intentional while Pencil + palm contact is present? Is palm rejection configurable at this level? Is there another public input API we should be using for this scenario? We’re currently testing UIEvent.coalescedTouches(for:) to determine whether additional genuine finger samples are available during these apparent gaps, but haven’t completed that test yet. Any guidance on whether this interaction is expected to be supportable through public UIKit APIs would be appreciated.
3
0
977
1d
PKCanvasView: Apple Pencil interrupts an active finger drawing with .anyInput
I’m testing simultaneous finger and Apple Pencil input with PencilKit and have reduced the behaviour to a minimal PKCanvasView. import SwiftUI struct ContentView: View { var body: some View { PencilCanvas() .ignoresSafeArea() } } struct PencilCanvas: UIViewRepresentable { func makeUIView(context: Context) -> PKCanvasView { let canvas = PKCanvasView() canvas.drawingPolicy = .anyInput return canvas } func updateUIView(_ canvas: PKCanvasView, context: Context) {} } On a physical iPad with Apple Pencil, I consistently see this behaviour: Start drawing with a finger and keep the finger moving. Touch the canvas with Apple Pencil. The active finger stroke immediately stops, while the Pencil can draw. The reverse order behaves differently: Start drawing with Apple Pencil and keep it moving. Touch/draw with a finger. The Pencil stroke continues rather than being cancelled. I’ve also confirmed that a newly created PKCanvasView reports isMultipleTouchEnabled == true, and explicitly setting it to true does not change the behaviour. Is simultaneous independent Apple Pencil and finger drawing supported by PKCanvasView when using .drawingPolicy = .anyInput? If so, is there a supported configuration or gesture-recognizer setting required to prevent the Pencil from cancelling an active finger stroke? Or is Pencil taking priority over an active finger drawing gesture expected behaviour in PencilKit?
3
0
882
Sep ’26
Finger input interrupted while drawing with Apple Pencil + palm resting on display
I’m investigating an issue with simultaneous Apple Pencil and finger input on iPad. Apple Pencil + finger input works correctly while the Pencil user’s hand/palm is off the display. However, when drawing naturally with Apple Pencil with the palm resting on the display, an existing finger drawing contact elsewhere on the screen can be cancelled and then stop receiving input for several seconds. Pencil input continues normally throughout. Initially I suspected PencilKit, but I’ve reproduced the underlying behaviour below PencilKit/SwiftUI. Instrumenting UIKit at UIApplication.sendEvent shows the finger touch being cancelled and, in some cases, no further events for that finger for ~4–5 seconds while Pencil MOVED events continue to arrive normally. Everything delivered to the application is accounted for, so this appears to occur before our drawing/rendering code. Is this expected behaviour from the iPad’s Pencil/palm rejection? More specifically: Is there any supported way to tell UIKit that an existing finger contact should remain intentional while Pencil + palm contact is present? Is palm rejection configurable at this level? Is there another public input API we should be using for this scenario? We’re currently testing UIEvent.coalescedTouches(for:) to determine whether additional genuine finger samples are available during these apparent gaps, but haven’t completed that test yet. Any guidance on whether this interaction is expected to be supportable through public UIKit APIs would be appreciated.
Replies
3
Boosts
0
Views
977
Activity
1d
PKCanvasView: Apple Pencil interrupts an active finger drawing with .anyInput
I’m testing simultaneous finger and Apple Pencil input with PencilKit and have reduced the behaviour to a minimal PKCanvasView. import SwiftUI struct ContentView: View { var body: some View { PencilCanvas() .ignoresSafeArea() } } struct PencilCanvas: UIViewRepresentable { func makeUIView(context: Context) -> PKCanvasView { let canvas = PKCanvasView() canvas.drawingPolicy = .anyInput return canvas } func updateUIView(_ canvas: PKCanvasView, context: Context) {} } On a physical iPad with Apple Pencil, I consistently see this behaviour: Start drawing with a finger and keep the finger moving. Touch the canvas with Apple Pencil. The active finger stroke immediately stops, while the Pencil can draw. The reverse order behaves differently: Start drawing with Apple Pencil and keep it moving. Touch/draw with a finger. The Pencil stroke continues rather than being cancelled. I’ve also confirmed that a newly created PKCanvasView reports isMultipleTouchEnabled == true, and explicitly setting it to true does not change the behaviour. Is simultaneous independent Apple Pencil and finger drawing supported by PKCanvasView when using .drawingPolicy = .anyInput? If so, is there a supported configuration or gesture-recognizer setting required to prevent the Pencil from cancelling an active finger stroke? Or is Pencil taking priority over an active finger drawing gesture expected behaviour in PencilKit?
Replies
3
Boosts
0
Views
882
Activity
Sep ’26