SwiftUI

Question

我有一个 LazyVGrid 和一个更改列数的 NavigationBarItem 按钮。它循环通过 1、2、3，然后回到 1，等等。我使用 .animation(.default) 修饰符来为这个变化设置动画。当只有一列时，我使用包含一个小地图元素的不同单元格结构。我有一个上下文菜单，它适用于 2 列和 3 列，但在单列单元格上使用时会立即崩溃。

AnimationError[2652:855376] [Unknown process name] CGImageCreate: invalid image alphaInfo: kCGImageAlphaNone. It should be kCGImageAlphaNoneSkipLast

此崩溃仅发生在我的 iPhone 11 Pro 真实设备 上，模拟器处理得很好。如果我删除动画，一切都很好。

可编译的精简版：

import SwiftUI
import CoreLocation
import MapKit

struct HillMO: Identifiable {
    let id = UUID()
    let name: String
    let latitude: Double
    let longitude: Double
}

struct ContentView: View {
    
    @State private var gridLayout: [GridItem] = [GridItem(), GridItem(), GridItem()]
    
    var body: some View {
        NavigationView {
            VStack {
                GeometryReader { geometry in
                    ScrollView {
                        LazyVGrid(columns: gridLayout, alignment: .center, spacing: 8) {
                            ForEach(hills) { hill in
                                Cell(hill: hill, width: geometry.size.width, columns: gridLayout.count)
                                    .contextMenu {
                                        Button(action: { }) { Label("Bingo", image: "eyeglasses") }
                                        Button(action: { }) { Label("Bungo", image: "hourglass") }
                                    }
                            }
                        }.padding(5)
                        .animation(.default)
                    }
                }
            }
            .navigationBarTitle("Bagger")
            .navigationBarItems(
                trailing: HStack {
                    Button(action: {
                        gridLayout = Array(repeating: .init(.flexible()), count: gridLayout.count % 3 + 1)
                    }) {
                        Image(systemName: "circle.grid.3x3")
                    }
                }
            )
        }
    }
    
    let hills = [ HillMO(name: "un", latitude: 0.0, longitude: 0.0),
                  HillMO(name: "dau", latitude: 1.0, longitude: 1.0),
                  HillMO(name: "tri", latitude: 2.0, longitude: 2.0),
                  HillMO(name: "pedwar", latitude: 3.0, longitude: 3.0),
                  HillMO(name: "pump", latitude: 4.0, longitude: 4.0),
                  HillMO(name: "chwech", latitude: 5.0, longitude: 5.0)
                ]
}

我的 Cell 和 CellMap 视图：

struct Cell: View {
    
    var hill: HillMO
    var width: CGFloat
    var columns: Int
    
    var body: some View {
        Group {
            if columns != 1 {
                ZStack {
                    Rectangle()
                    Text(hill.name).foregroundColor(.white)
                }
            } else {
                ZStack {
                    Rectangle()
                    HStack {
                        Text(hill.name).foregroundColor(.white)
                        Spacer()
                        CellMap(coordinateRegion: MKCoordinateRegion(center: CLLocationCoordinate2D(latitude: hill.latitude, longitude: hill.longitude),
                                                                     latitudinalMeters: 300000,
                                                                     longitudinalMeters: 300000))
                            .frame(width: (width / CGFloat(columns)) * 0.24, height: (width / CGFloat(columns)) * 0.24)
                            .clipShape(Circle())
                    }
                }
            }
        }
        .frame(height: (width / CGFloat(columns)) * (columns == 1 ? 0.25 : 1.25))
    }
}

struct CellMap: View {
    
    @State var coordinateRegion: MKCoordinateRegion
    
    var body: some View {
        Map(coordinateRegion: $coordinateRegion)
    }
}

Answer 1

尽量将动画限制为准确的状态值

}.padding(5)
.animation(.default, value: gridLayout)

这将需要使 HillMO 平等

struct HillMO: Identifiable, Equatable {
    static func == (lhs: Self, rhs: Self) -> Bool {
        lhs.id == rhs.id
    }

    let id = UUID()
    let name: String
    let latitude: Double
    let longitude: Double
}

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