SwiftUI 放大手势 onUpdate 不会在设备上立即触发(适用于模拟器)

Question

我的放大手势的 onUpdate 属性会立即在模拟器上触发，但不会在设备上触发

我已经尝试删除所有其他手势。似乎无所谓。在 iOS 13.1 和 13.2 以及 xcode 11.1 和 11.2 上试过

import UIKit

struct ContentView: View {

    @State var gridDraggedX: CGFloat = 0
    @State var gridDraggedY: CGFloat = 0
    @State var accumulatedGridDraggedX: CGFloat = 0
    @State var accumulatedGridDraggedY: CGFloat = 0
    private var numCells: CGFloat = 10

    var dimension: CGFloat {
        numCells * cellSize
    }

    @State var initialCellSize: CGFloat = 50.0
    @State var cellSize: CGFloat = 50.0

    var body: some View {

        let dragGesture = DragGesture(minimumDistance: 5.0, coordinateSpace: .global)
            .onChanged({ value in
                self.gridDraggedX = value.translation.width + self.accumulatedGridDraggedX
                self.gridDraggedY = value.translation.height + self.accumulatedGridDraggedY
            }).onEnded({ value in
                self.gridDraggedX = value.translation.width + self.accumulatedGridDraggedX
                self.gridDraggedY = value.translation.height + self.accumulatedGridDraggedY
                self.accumulatedGridDraggedX = self.gridDraggedX
                self.accumulatedGridDraggedY = self.gridDraggedY
            })

        let dragGesture2 = DragGesture(minimumDistance: 0.0, coordinateSpace: .global)
            .onEnded({ value in
                if value.translation.width == 0 && value.translation.height == 0 {
                    print(value.startLocation)
                }
            })

        let magGesture = MagnificationGesture(minimumScaleDelta: 0.0).onChanged({ value in
                print(value)
                self.cellSize = self.initialCellSize * value
            }).onEnded({ value in
                self.cellSize = self.initialCellSize * value
                self.initialCellSize = self.cellSize
            })

        return ZStack(alignment: .topLeading) {
            GeometryReader { geometry in
                Path { path in
                    path.move(to: CGPoint(x:0, y: 0))
                    path.addLine(to: CGPoint(x: 0, y: self.dimension))
                    path.addLine(to: CGPoint(x: self.dimension, y: self.dimension))
                    path.addLine(to: CGPoint(x: self.dimension, y: 0))
                    path.addLine(to: CGPoint(x: 0, y: 0))
                }.fill(Color.red)
                Path { path in
                    for i in (0...Int(self.numCells)) {
                        path.move(to: CGPoint(x: 0 + CGFloat(i) * self.cellSize, y: 0))
                        path.addLine(to: CGPoint(x: 0 + CGFloat(i) * self.cellSize, y: self.dimension))
                    }
                    for i in (0...Int(self.numCells)) {
                        path.move(to: CGPoint(x: 0, y: 0 + CGFloat(i) * self.cellSize))
                        path.addLine(to: CGPoint(x: self.dimension, y: 0 + CGFloat(i) * self.cellSize))
                    }
                }.stroke(Color.blue)
                }.offset(x: gridDraggedX, y: gridDraggedY).simultaneousGesture(dragGesture).simultaneousGesture(dragGesture2).simultaneousGesture(magGesture)
        }
    }
}

我希望 magGesture 的 onUpdate 在用户开始捏合时立即触发。直到立即 magGesture onUpdate 才会触发。在模拟器上使用

编辑:所以在设备上它似乎很挑剔。如果你的两个捏手指中的一个没有移动，那么它不会触发 onUpdate 直到该值高于某个阈值。哇哦

Answer 1

所以在设备上它似乎只是非常挑剔。如果你的两个捏手指中的一个没有移动，那么它不会触发 onUpdate 直到该值高于某个阈值。 oof - 这个阈值似乎是任意的。也可能只是我的第二根手指移动的那一刻，达到一定的速度，或者其他我不知道的东西