当计时器为 运行 时，SwiftUI ActionSheet 不会关闭

Question

我有以下简单的 SwiftUI 设置。 运行 并更新文本的计时器。如果计时器不是 运行（停止或暂停），我可以轻松显示 ActionSheet（通过点击操作）并通过选择“取消”或“操作 1”选项将其关闭。但是如果计时器是 运行，我真的很难通过选择“取消”或“操作 1”选项之一来关闭 ActionSheet。你知道这是怎么回事吗？

我正在使用 Xcode 11.5.

import SwiftUI

struct ContentView: View {
    
    @ObservedObject var stopWatch = StopWatch()
    @State private var showActionSheet: Bool = false
    
    var body: some View {
        VStack {
            Text("\(stopWatch.secondsElapsed)")
            HStack {
                if stopWatch.mode == .stopped {
                    Button(action: { self.stopWatch.start() }) {
                        Text("Start")
                    }
                } else if stopWatch.mode == .paused {
                    Button(action: { self.stopWatch.start() }) {
                        Text("Resume")
                    }
                } else if stopWatch.mode == .running {
                    Button(action: { self.stopWatch.pause() }) {
                        Text("Pause")
                    }
                }
                Button(action: { self.stopWatch.stop() }) {
                    Text("Reset")
                }
            }
            Button(action: { self.showActionSheet = true }) {
                Text("Actions")
            }
            .actionSheet(isPresented: $showActionSheet) {
                ActionSheet(title: Text("Actions"), message: nil, buttons: [.default(Text("Action 1")), .cancel()])
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

import SwiftUI

class StopWatch: ObservableObject {
    
    @Published var secondsElapsed: TimeInterval = 0.0
    @Published var mode: stopWatchMode = .stopped
    
    var timer = Timer()
    func start() {
        mode = .running
        timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { timer in
            self.secondsElapsed += 0.1
        }
    }
    
    func stop() {
        timer.invalidate()
        secondsElapsed = 0
        mode = .stopped
    }
    
    func pause() {
        timer.invalidate()
        mode = .paused
    }
    
    enum stopWatchMode {
        case running
        case stopped
        case paused
    }
}

Answer 1

与 Xcode 12 / iOS 14 一起工作正常，但尝试将带有 sheet 的按钮分离到另一个子视图中，以避免在计时器计数器刷新时重新创建它。

测试 Xcode 12 / iOS 14

struct ContentView: View {

    @ObservedObject var stopWatch = StopWatch()
    // @StateObject var stopWatch = StopWatch()       // << used for SwiftUI 2.0
    @State private var showActionSheet: Bool = false

    var body: some View {
        VStack {
            Text("\(stopWatch.secondsElapsed)")
            HStack {
                if stopWatch.mode == .stopped {
                    Button(action: { self.stopWatch.start() }) {
                        Text("Start")
                    }
                } else if stopWatch.mode == .paused {
                    Button(action: { self.stopWatch.start() }) {
                        Text("Resume")
                    }
                } else if stopWatch.mode == .running {
                    Button(action: { self.stopWatch.pause() }) {
                        Text("Pause")
                    }
                }
                Button(action: { self.stopWatch.stop() }) {
                    Text("Reset")
                }
            }
            ActionsSubView(showActionSheet: $showActionSheet)
        }
    }
}

struct ActionsSubView: View {
    @Binding var showActionSheet: Bool
    var body: some View {
        Button(action: { self.showActionSheet = true }) {
            Text("Actions")
        }
        .actionSheet(isPresented: $showActionSheet) {
            ActionSheet(title: Text("Actions"), message: nil, buttons: [.default(Text("Action 1")), .cancel()])
        }
    }
}