How to get local tap position in onTapGesture?

user_12134656 0
Viewed 5107

Have some rendered image and need to determine tap position relative to image. Seems to be simple, but can't find the answer

  var body: some View {
    VStack {
      Image(uiImage: drawRectangle()) // some rendered image
        .onTapGesture {
          // print(x, y)?
        }
swiftui
2 Answers

Found this solution:

        .gesture(
            DragGesture(minimumDistance: 0, coordinateSpace: .global)
                .onChanged { value in
                  self.position = value.location
                }
                .onEnded { _ in
                  self.position = .zero
                }
        )

setting minimumDistance: 0 will call onChanged immediately

user_121346560

I did try using DragGesture with minimumDistance: 0 but it hijacks my table view's scroll gesture.

So I preferred to use a proper UITapGestureRecognizer added to a plain transparent UIView embed in aTappableView SwitUI UIViewRepresentable instead.

struct TappableView: UIViewRepresentable
{
    var tapCallback: (UITapGestureRecognizer) -> Void

    typealias UIViewType = UIView

    func makeCoordinator() -> TappableView.Coordinator
    {
        Coordinator(tapCallback: self.tapCallback)
    }

    func makeUIView(context: UIViewRepresentableContext<TappableView>) -> UIView
    {
        let view = UIView()
        view.addGestureRecognizer(UITapGestureRecognizer(target: context.coordinator, action: #selector(Coordinator.handleTap(sender:))))
        return view
    }

    func updateUIView(_ uiView: UIView, context: UIViewRepresentableContext<TappableView>)
    {
    }

    class Coordinator
    {
        var tapCallback: (UITapGestureRecognizer) -> Void

        init(tapCallback: @escaping (UITapGestureRecognizer) -> Void)
        {
            self.tapCallback = tapCallback
        }

        @objc func handleTap(sender: UITapGestureRecognizer)
        {
            self.tapCallback(sender)
        }
    }
}

Then just add it as a .overlay to the SwiftUI view you want taps added to.

.overlay(
    TappableView { gesture in
        // Just use the regular UIKit gesture as you want!
})
user_10491340
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