Two finger tap gesture in SwiftUI

Question

harald_n OP

Created May ’20

Replies 3

Boosts 0

Views 5.5k

Participants 3

I would like to recognize to a tab gesture in SwiftUI with two fingers.

How do I change the code

 var body: some View {
    Image("tap-image")
        .gesture(
            TapGesture()
                .onEnded({
                    print("Tapped!")
                })
        )
}

if I only want to react to the gesture with two fingers?

Thanks,

Harald

Answered by harald_n in 419258022

Thanks Claude,

I hope the next version of SwiftUI will handle this better.

This is my code:

 struct ContentView: View {
    var body: some View {
        Rectangle()
            .fill(Color.black)
            .frame(width: 200, height: 200)
            .overlay(
            TappableView { gesture in
                print("2 touches detected")
            })
    }
}

 import SwiftUI
 
struct TappableView: UIViewRepresentable
{
    var tapCallback: (UITapGestureRecognizer) -> Void
 
    typealias UIViewType = UIView
 
    func makeCoordinator() -> TappableView.Coordinator
    {
        Coordinator(tapCallback: self.tapCallback)
    }
 
    func makeUIView(context: UIViewRepresentableContext) -> UIView
    {
        let view = UIView()
        let doubleTapGestureRecognizer = UITapGestureRecognizer(target: context.coordinator, action: #selector(Coordinator.handleTap(sender:)))
       
        /// Set number of touches.
        doubleTapGestureRecognizer.numberOfTouchesRequired = 2
       
        view.addGestureRecognizer(doubleTapGestureRecognizer)
        return view
    }
 
    func updateUIView(_ uiView: UIView, context: UIViewRepresentableContext)
    {
    }
 
    class Coordinator
    {
        var tapCallback: (UITapGestureRecognizer) -> Void
 
        init(tapCallback: @escaping (UITapGestureRecognizer) -> Void)
        {
            self.tapCallback = tapCallback
        }
 
        @objc func handleTap(sender: UITapGestureRecognizer)
        {
            self.tapCallback(sender)
        }
    }
}

Boost

Answer 1

Claude31 OP

May ’20

I found nowhere in doc the equivalent of UIKit numberOfTouches.

I don't know if you could create a UIKit gesture and use it here.

May have a look here for some hint:

https://stackoverflow.com/questions/57577901/how-to-handle-touch-gestures-in-swiftui-in-swift-uikit-map-component

0

Answer 2

harald_n OP

May ’20

Accepted Answer

Thanks Claude,

I hope the next version of SwiftUI will handle this better.

This is my code:

 struct ContentView: View {
    var body: some View {
        Rectangle()
            .fill(Color.black)
            .frame(width: 200, height: 200)
            .overlay(
            TappableView { gesture in
                print("2 touches detected")
            })
    }
}

 import SwiftUI
 
struct TappableView: UIViewRepresentable
{
    var tapCallback: (UITapGestureRecognizer) -> Void
 
    typealias UIViewType = UIView
 
    func makeCoordinator() -> TappableView.Coordinator
    {
        Coordinator(tapCallback: self.tapCallback)
    }
 
    func makeUIView(context: UIViewRepresentableContext) -> UIView
    {
        let view = UIView()
        let doubleTapGestureRecognizer = UITapGestureRecognizer(target: context.coordinator, action: #selector(Coordinator.handleTap(sender:)))
       
        /// Set number of touches.
        doubleTapGestureRecognizer.numberOfTouchesRequired = 2
       
        view.addGestureRecognizer(doubleTapGestureRecognizer)
        return view
    }
 
    func updateUIView(_ uiView: UIView, context: UIViewRepresentableContext)
    {
    }
 
    class Coordinator
    {
        var tapCallback: (UITapGestureRecognizer) -> Void
 
        init(tapCallback: @escaping (UITapGestureRecognizer) -> Void)
        {
            self.tapCallback = tapCallback
        }
 
        @objc func handleTap(sender: UITapGestureRecognizer)
        {
            self.tapCallback(sender)
        }
    }
}

3

Answer 3

cesmejia OP

Jul ’24

This is now solved on iOS 18: Multiple finger / Multitouch recognition is now possible in SwiftUI by using 'SpatialEventGesture'. Apple documentation link: https://developer.apple.com/documentation/swiftui/spatialeventgesture

0

	var body: some View {
	Image("tap-image")
	.gesture(
	TapGesture()
	.onEnded({
	print("Tapped!")
	})
	)
	}

	struct ContentView: View {
	var body: some View {
	Rectangle()
	.fill(Color.black)
	.frame(width: 200, height: 200)
	.overlay(
	TappableView { gesture in
	print("2 touches detected")
	})
	}
	}

	import SwiftUI

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

	typealias UIViewType = UIView

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

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

	/// Set number of touches.
	doubleTapGestureRecognizer.numberOfTouchesRequired = 2

	view.addGestureRecognizer(doubleTapGestureRecognizer)
	return view
	}

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

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

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

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