SwiftUI:如何在视图关闭时维护onReceive

Question

import SwiftUI

struct TimerView: View {

@EnvironmentObject var tm : TimerModel

@State var timerStyle : TimerStyle?
@State var focusColors : [Color] = [Color.green, Color.mint, Color.green, Color.mint, Color.green]
@State var breakColors : [Color] = [Color.blue, Color.mint, Color.blue, Color.mint, Color.blue]
@State var longBreakColors : [Color] = [Color.gray, Color.white, Color.gray, Color.white, Color.gray]
@State var isShowNewTimerView : Bool = false
var body: some View {
NavigationView {
ZStack {
Color("BackgroundColor").ignoresSafeArea(.all)
if tm.timerStyle == nil {
NoTimerView()
} else {
VStack(alignment : .center, spacing: 40){
Spacer()
if let timerStyle = tm.timerStyle {
switch timerStyle {
case .focus:
Text("Focus Mode 🔥")
.font(.system(size: 30, weight: .bold, design: .rounded))
.fontWeight(.bold)

case .short:
Text("Break Mode ☕️")
.font(.system(size: 30, weight: .bold, design: .rounded))
.fontWeight(.bold)

case .long:
Text("Long Break Mode 🌕")
.font(.system(size: 30, weight: .bold, design: .rounded))
.fontWeight(.bold)//
}
}

if let timerStyle = tm.timerStyle {
switch timerStyle {
case .focus:
ProgressView(progress: tm.progress, gradientColors: focusColors, time: formatTime())
.padding()
.onReceive(tm.timer) { _ in
if tm.timerMode == .start {
if tm.elapsedFocusTime != 0 {
tm.trackFocusProgress()
} else {
if tm.isAuto {
tm.timerStyle = .short
tm.progress = 0
tm.elapsedShortTime = tm.totalShortTime

if tm.isOnSound {
playSound(sound: "chimeup", type: "mp3")
}
} else {
tm.timerMode = .normal
tm.timerStyle = .short
tm.isStarted = false
tm.progress = 0
tm.elapsedShortTime = tm.totalShortTime
audioPlayer1?.stop()

if tm.isOnSound {
playSound(sound: "chimeup", type: "mp3")
}
}
}
}
}
case .short:
ProgressView(progress: tm.progress, gradientColors: breakColors, time: formatTime())
.padding()
.onReceive(tm.timer) { _ in
if tm.timerMode == .start {
if tm.elapsedShortTime != 0 {
tm.trackFocusProgress()
} else {
if tm.isAuto {
if tm.isSkipMode {
tm.timerStyle = .focus
tm.progress = 0
tm.elapsedFocusTime = tm.totalFocusTime

if tm.isOnSound {
playSound(sound: "chimeup", type: "mp3")
}

} else {
tm.timerStyle = .long
tm.progress = 0
tm.elapsedLongBreakTime = tm.totalLongBreakTime
if tm.isOnSound {
playSound(sound: "chimeup", type: "mp3")
}
}
} else {
if tm.isSkipMode {
tm.timerStyle = .focus
tm.timerMode = .normal
tm.timerStyle = .focus
tm.isStarted = false
tm.progress = 0
tm.elapsedFocusTime = tm.totalFocusTime
audioPlayer1?.stop()

if tm.isOnSound {
playSound(sound: "chimeup", type: "mp3")
}

} else {
tm.timerMode = .normal
tm.timerStyle = .long
tm.isStarted = false
tm.progress = 0
tm.elapsedLongBreakTime = tm.totalLongBreakTime
audioPlayer1?.stop()

if tm.isOnSound {
playSound(sound: "chimeup", type: "mp3")
}
}
}
}
}
}
case .long:
ProgressView(progress: tm.progress, gradientColors: longBreakColors, time: formatTime())
.padding()
.onReceive(tm.timer) { _ in
if tm.timerMode == .start {
if tm.elapsedLongBreakTime != 0 {
tm.trackFocusProgress()
} else {
if tm.isAuto {
tm.timerStyle = .focus
tm.progress = 0
tm.elapsedFocusTime = tm.totalFocusTime

if tm.isOnSound {
playSound(sound: "chimeup", type: "mp3")
}

} else {
tm.timerMode = .normal
tm.timerStyle = .focus
tm.isStarted = false
tm.progress = 0
tm.elapsedFocusTime = tm.totalFocusTime
audioPlayer1?.stop()

if tm.isOnSound {
playSound(sound: "chimeup", type: "mp3")
}
}
}
}
}
}
}

if let timerStyle = tm.timerStyle {
switch timerStyle {
case .focus:
Text("Let's concentrate on your task!")
.font(.headline)
.multilineTextAlignment(.center)
case .short:
Text("Well done, Have a short break!")
.font(.headline)
.multilineTextAlignment(.center)
case .long:
Text("It's so long journey, take care yourself.")
.font(.headline)
.multilineTextAlignment(.center)
}
}

HStack {

Button(action: {
switch tm.timerMode {

case .normal:
tm.timerMode = .start
tm.isStarted.toggle()
tm.backBroundMusic()

case .start:
audioPlayer1?.stop()
tm.timerMode = .normal

if let timerStyle = tm.timerStyle {
switch timerStyle {
case .focus:
tm.progress = 0
tm.elapsedFocusTime = tm.totalFocusTime

case .short:
tm.progress = 0
tm.elapsedShortTime = tm.totalShortTime

case .long:
tm.progress = 0
tm.elapsedLongBreakTime = tm.totalLongBreakTime
}
}

tm.isStarted.toggle()

case .pause:

tm.isStarted.toggle()
tm.isPaused.toggle()
tm.timerMode = .normal

if let timerStyle = tm.timerStyle {
switch timerStyle {
case .focus:
tm.progress = 0
tm.elapsedFocusTime = tm.totalFocusTime

case .short:
tm.progress = 0
tm.elapsedShortTime = tm.totalShortTime

case .long:
tm.progress = 0
tm.elapsedLongBreakTime = tm.totalLongBreakTime
}
}

case .stop:
tm.timerMode = .normal
}
}, label: {
Image(systemName: tm.isStarted ? "square.fill":"play.fill")
.frame(width : 60, height : 60)
.background(tm.isStarted ? .red : .green)
.foregroundColor(.white)
.font(.title)
.cornerRadius(10)
.shadow(color: .gray.opacity(0.5), radius: 1, x: 1, y: 1)
})
.disabled(tm.timerStyle == nil)
.padding()

Button(action:  {
switch tm.timerMode {
case .normal:
return
case .start:
audioPlayer1?.stop()
tm.timerMode = .pause
tm.isPaused.toggle()
case .pause:
tm.backBroundMusic()
tm.timerMode = .start
tm.isPaused.toggle()
case .stop:
return
}
}, label: {
Image(systemName: tm.timerMode == .pause
? "play.fill" : "pause.fill")
.frame(width : 60, height : 60)
.background(tm.timerMode == .normal ? .gray : .yellow)
.foregroundColor(.white)
.font(.title)
.cornerRadius(10)
.shadow(color: .gray.opacity(0.5), radius: 1, x: 1, y: 1)
})
.disabled(tm.timerStyle == nil)
.padding()

Button(action:  {

audioPlayer1?.stop()

if let timerStyle = tm.timerStyle {
switch timerStyle {
case .focus:
tm.timerMode = .normal
tm.timerStyle = .short
tm.isStarted = false
tm.progress = 0
tm.elapsedShortTime = tm.totalShortTime
case .short:
if tm.isSkipMode {
tm.timerMode = .normal
tm.timerStyle = .focus
tm.isStarted = false
tm.progress = 0
tm.elapsedFocusTime = tm.totalFocusTime
} else {
tm.timerMode = .normal
tm.timerStyle = .long
tm.isStarted = false
tm.progress = 0
tm.elapsedLongBreakTime = tm.totalLongBreakTime
}
case .long:
tm.timerMode = .normal
tm.timerStyle = .focus
tm.isStarted = false
tm.progress = 0
tm.elapsedFocusTime = tm.totalFocusTime
}
}
}, label: {
Image(systemName: "forward.end.fill")
.frame(width : 60, height : 60)
.background(.blue)
.foregroundColor(.white)
.font(.title)
.cornerRadius(10)
.shadow(color: .gray.opacity(0.5), radius: 1, x: 1, y: 1)
})
.disabled(tm.timerStyle == nil)
.padding()

} // hst
Spacer()
}//vst
}
}//Zstack
.navigationTitle("PPO.MO ⏱")
.navigationBarTitleDisplayMode(.inline)
.navigationBarItems(trailing:
HStack{

if tm.isOnBackgroundSound {
Menu {
Button(action: {
switch tm.timerMode {
case .normal:
tm.backgroundNoise = .forest
case .start:
tm.backgroundNoise = .forest
tm.backBroundMusic()
case .pause:
audioPlayer1?.stop()
case .stop:
tm.backgroundNoise = .forest
}

}, label: {
Label(tm.backgroundNoise == .forest ? "✅ Forest" : "Forest", systemImage: "leaf")
})

Button(action: {
switch tm.timerMode {
case .normal:
tm.backgroundNoise = .river
case .start:
tm.backgroundNoise = .river
tm.backBroundMusic()
case .pause:
audioPlayer1?.stop()
case .stop:
tm.backgroundNoise = .river
}
}, label: {
Label(tm.backgroundNoise == .river ? "✅ River" : "River", systemImage: "drop.circle")
})

Button(action: {
switch tm.timerMode {
case .normal:
tm.backgroundNoise = .rain
case .start:
tm.backgroundNoise = .rain
tm.backBroundMusic()
case .pause:
audioPlayer1?.stop()
case .stop:
tm.backgroundNoise = .rain
}
}, label: {
Label(tm.backgroundNoise == .rain ? "✅ Rain" : "Rain", systemImage: "cloud.rain")
})

Button(action: {
switch tm.timerMode {
case .normal:
tm.backgroundNoise = .wave
case .start:
tm.backgroundNoise = .wave
tm.backBroundMusic()
case .pause:
audioPlayer1?.stop()
case .stop:
tm.backgroundNoise = .wave
}
}, label: {
Label(tm.backgroundNoise == .wave ? "✅ Wave" : "Wave", systemImage: "cloud.rain")
})

Button(action: {
tm.backgroundNoise = .turnOff
audioPlayer1?.stop()
}, label: {
Label(tm.backgroundNoise == .turnOff ? "✅ Turn off" : "Turn off", systemImage: "speaker.slash")
})

} label: {
Image(systemName: tm.backgroundNoise == .turnOff ? "speaker.slash.circle" : "speaker.circle")
}
}

NavigationLink(destination: {
AddTimerView()
}, label: {
Image(systemName: "plus")
})
.simultaneousGesture(TapGesture().onEnded({
tm.timerMode = .pause
audioPlayer1?.stop()
}))
})
}//nav
}
}
extension TimerView {

func formatTime() -> String {

if let timerStyle = tm.timerStyle {
switch timerStyle {
case .focus:
let minute = Int(tm.elapsedFocusTime) / 60 % 60
let second = Int(tm.elapsedFocusTime) % 60

return String(format: "%02i:%02i", minute, second)
case .short:
let minute = Int(tm.elapsedShortTime) / 60 % 60
let second = Int(tm.elapsedShortTime) % 60

return String(format: "%02i:%02i", minute, second)
case .long:
let minute = Int(tm.elapsedLongBreakTime) / 60 % 60
let second = Int(tm.elapsedLongBreakTime) % 60

return String(format: "%02i:%02i", minute, second)
}
}
return "00:00"
}
}

嗨，我正在试着自己制作pomodoro计时器。

但是，当我检查错误时，我发现当视图通过向上滑动关闭时，我的onReceive修改器会关闭。

当这样做时，计时器停止，我认为onReceive不工作。

所以，我想知道如何在视图向下滑动的情况下保持onreceive。

Answer 1

在一些始终显示的视图上放置onReceive，如

var body: some View {
NavigationView {
ZStack {
Color("BackgroundColor").ignoresSafeArea(.all)
.onReceive(tm.timer) { _ in               // << here !!

从处理目的来看，它在哪里使用并不重要。