Use multiple gestures to interact with an object.

SwiftUIGestures.swift

// SwiftUI Gestures Tiny Example
// Xcode 12.3
// This gist shows how to use multiple gestures on same object.
// We draw a rectangle on screen that can be 
// 1. pinch zoomed
// 2. rotated
// 3. tapped (single tap) to change opacity
// 4. tapped (double tap) to change color
// 5. long press to scale up (+0.2)

import SwiftUI

struct ContentView: View {
    @State var translationXDuringDrag: CGFloat = 0.0
    @State var translationYDuringDrag: CGFloat = 0.0
    @State var translationXCumulative: CGFloat = 0.0
    @State var translationYCumulative: CGFloat = 0.0
    
    @State var transientZoomScale: CGFloat = 1.0
    @State var steadyStateZoomScale: CGFloat = 1.0
    
    @State var alpha: CGFloat = 0.3
    
    @State var color: UIColor?
    
    @State var transientRotation: Angle = Angle.init(degrees: 0)
    @State var steadyStateRotation: Angle = Angle.init(degrees: 0)
    
    let colors = [UIColor.blue, UIColor.systemPink, UIColor.yellow, UIColor.green]
    
    var zoomScale: CGFloat {
        transientZoomScale * steadyStateZoomScale
    }
    
    var rotation: Angle {
        steadyStateRotation + transientRotation
    }
    
    var body: some View {
        VStack {
            Color(color == nil ? UIColor.blue.withAlphaComponent(alpha) : color!.withAlphaComponent(alpha))
                .frame(width: 200, height: 200, alignment: .center)
                .cornerRadius(10)
                .scaleEffect(zoomScale)
                .rotationEffect(rotation)
                .transformEffect(.init(translationX: translationXCumulative+translationXDuringDrag, y: translationYCumulative+translationYDuringDrag))
                .gesture(dragGesture)
                .gesture(rotationAndMagnification)
                .onTapGesture(count: 2) {
                    color = colors.filter {$0 != color}.randomElement()
                }
                .onTapGesture {
                    alpha += 0.2
                    if alpha > 0.8 {
                        alpha = 0.1
                    }
                }
                .onLongPressGesture {
                    withAnimation {
                        steadyStateZoomScale += 0.2
                    }
                }
        }
        .background(Text(
            """
                        box can be
                        1. dragged
                        2. pinch zoomed/rotated.
                        3. Single tap to change alpha
                        4. Double tap changes color
                        5. Long press zooms up incrementally
                        """
        ))
    }
    var dragGesture: some Gesture {
        DragGesture()
            .onChanged { (value) in
                translationXDuringDrag = value.translation.width
                translationYDuringDrag = value.translation.height
            }
            .onEnded { value in
                translationXCumulative += value.translation.width
                translationYCumulative += value.translation.height
                translationXDuringDrag = 0
                translationYDuringDrag = 0
            }
    }
    var magnificationGesture: some Gesture {
        MagnificationGesture()
            .onChanged({ (value) in
                transientZoomScale = value
            })
            .onEnded { (finalValue) in
                transientZoomScale = 1
                steadyStateZoomScale *= finalValue
            }
    }
    var rotationGesture: some Gesture {
        RotationGesture()
            .onChanged { (angle) in
                transientRotation = angle
            }
            .onEnded { (finalAngle) in
                steadyStateRotation += finalAngle
                transientRotation = Angle()
            }
    }
    var rotationAndMagnification: some Gesture {
        rotationGesture.simultaneously(with: magnificationGesture)
    }
}