SwiftUI: ListItem gestures

问题

Target is a modification with the following behavior:

(but only with 2 buttons - 1 on the left side, 1 on the right)

Behavior:

short swipe shows the buttons and gives the user the ability to click it.
strong long swipe presses button.
ability to use 2 finger gesture

Minimal reproducible example:

import SwiftUI

public extension View {
    func SwiperizeItem(closureL: @escaping () -> (), closureR: @escaping () -> ()) -> some View
    {
        self.modifier( SwiperizeItemModifier(closureL: closureL, closureR: closureR) )
    }
}

struct SwiperizeItemModifier: ViewModifier {
    @State var dragOffset = CGSize.zero
    
    @State var offset1Shown = CGSize(width: 100, height: 0)
    @State var offset1Click = CGSize(width: 250, height: 0)
    
    @State var offset2Shown = CGSize(width: -100, height: 0)
    @State var offset2Click = CGSize(width: -250, height: 0)
    
    @State var BackL = Color.green
    @State var BackR = Color.red
    @State var ForeColorL = Color.white
    @State var ForeColorR = Color.white
    
    @State var closureL: () -> Void
    @State var closureR: () -> Void
    
    func body(content: Content) -> some View {
        HStack{
            Button(action: { closureL() } ) {
                Text("Left")
                    .foregroundColor(ForeColorL)
                    
            }
            .background(BackL)
            .frame(maxWidth: dragOffset.width > 0 ? dragOffset.width : 0)
            .fixedSize()
            
            
            content
                //.padding([.leading, .trailing], 20)
                .animation(.spring())
                .offset(x: self.dragOffset.width)
                .gesture(DragGesture()
                            .onChanged(){
                                value in
                                self.dragOffset = value.translation
                            }
                            .onEnded(){
                                value in
                                if ( dragOffset.width > 0 ) {
                                    if ( dragOffset.width < offset1Shown.width) {
                                        self.dragOffset = .zero
                                    }
                                    else if ( dragOffset.width > offset1Shown.width &&  dragOffset.width < offset1Click.width ) {
                                        self.dragOffset = offset1Shown
                                    }
                                    else if ( dragOffset.width > offset1Click.width ) {
                                        self.dragOffset = .zero
                                        closureR()
                                    }
                                }
                                else {
                                    if ( dragOffset.width > offset2Shown.width) {
                                        self.dragOffset = .zero
                                    }
                                    else if ( dragOffset.width < offset2Shown.width && dragOffset.width > offset2Click.width ) {
                                        self.dragOffset = offset2Shown
                                    }
                                    else if ( dragOffset.width < offset2Click.width ) {
                                        self.dragOffset = .zero
                                        closureL()
                                    }
                                }
                            }
                )
        
        }
    }
}



// ____________________

struct GuestureItem_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            Text("Hello")
                .padding(.all, 30)
                .background( Color( NSColor.red ) )
                .SwiperizeItem(closureL: { print("click left") }, closureR: { print("click right") })
        }
    }
}

So... my problems are:

to draw buttons like here using SwiftUI:

I think the solution may be related to the new release of SwiftUI components: LazyHGrid or OutlineGroup. https://developer.apple.com/videos/play/wwdc2020/10031

.onDelete() is not a solution for me because it's impossible to do 2 side buttons and impossible to edit "delete" text

how to make 2 fingers swipe using swiftUI? (less important)

回答1:

"How to implement swipe to delete?"

As long as you don't want to create custom UI for the delete button, you can take advantage of SwiftUI and use all of the built in features.

ForEach has a modifier called .onDelete, that gives you an IndexSet. This represents the rows that should be deleted when the user swipes. Now if we implement the necessary logic and wrap it in an animation block, everything will work as needed.

struct ContentView: View {
    @State var cars = ["Tesla Model 3", "BMW i3", "Roadster", "Cybertruck", "Agera Koenigsegg", "Rimac Concept One"]

    var body: some View {
        NavigationView {
            List {
                ForEach(cars, id: \.self) { car in
                    Text(car)
                }
                .onDelete { indexSet in
                    withAnimation {
                        cars.remove(atOffsets: indexSet)
                    }
                }
            }
            .navigationTitle("My Cars")
        }
    }
}

Note: .onDelete modifier is not available to use with List, can only be applied on ForEach.

"How to make a 2 fingers swipe gesture in SwiftUI?"

As of now SwiftUI does not have support for creating gestures for multiple fingers. The only solution is to use UIViewRepresentable in combination with UIPanGestureRecognizer. Then you can set the minimumNumberOfTouches to 2 fingers.

This post from Apple Developer Forum shows how you could achieve something similar for a simple 2 fingers tap gesture, but the idea and concept for swipe are very similar and already explained above.

Hope this helps! 😊

回答2:

Unfortunately there isn't any native SwiftUI solution so far (as of SwiftUI 2 beta).

SwiftUI - Still no support for custom swipe actions
How is possible configure the List "onDelete" action / Button?
SwiftUI - List editing mode - how to change delete button title?

You can make your custom swipe actions using UIKit and wrap them in UIViewRepresentable.

Some solutions (you may have seen them already):

SwiftUI - Custom Swipe Actions In List
Create gesture to edit list item using SwiftUI

Or you can just use a library instead (at least until a native solution is developed).

Some libraries:

SwipeCell (SwiftUI) (may be exactly what you need)
SwipeCellKit (UIKit)

If you want to implement simultaneous swipe gesture you need to use UIViewRepresentable again:

How to detect a tap gesture location in SwiftUI? (this is for tap gestures only but with nice explanation)
SwiftUI: Multitouch gesture / Multiple Gestures (this is the adaptation of the above but with swipe gestures)

Summing up

Answer to the first question: SwipeCell
Answer to the second question: SwiftUI: Multitouch gesture / Multiple Gestures

来源：https://stackoverflow.com/questions/62640289/swiftui-listitem-gestures

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