SwiftUI-如何创建启动/停止计时器
我的目标是在SwiftUI中创建一个以0开头的视图。当您按下视图时,计时器应开始向上计数,再次轻敲将停止计时器。最后,当您再次点击启动计时器时,计时器应在0开始 这是我目前的代码:SwiftUI-如何创建启动/停止计时器,swift,view,timer,swiftui,Swift,View,Timer,Swiftui,我的目标是在SwiftUI中创建一个以0开头的视图。当您按下视图时,计时器应开始向上计数,再次轻敲将停止计时器。最后,当您再次点击启动计时器时,计时器应在0开始 这是我目前的代码: import SwiftUI struct TimerView: View { @State var isTimerRunning = false @State private var endTime = Date() @State private var startTime = Date
import SwiftUI
struct TimerView: View {
@State var isTimerRunning = false
@State private var endTime = Date()
@State private var startTime = Date()
let timer = Timer.publish(every: 0.001, on: .main, in: .common).autoconnect()
var tap: some Gesture {
TapGesture(count: 1)
.onEnded({
isTimerRunning.toggle()
})
}
var body: some View {
Text("\(endTime.timeIntervalSince1970 - startTime.timeIntervalSince1970)")
.font(.largeTitle)
.gesture(tap)
.onReceive(timer) { input in
startTime = isTimerRunning ? startTime : Date()
endTime = isTimerRunning ? input : endTime
}
}
}
这段代码会导致计时器立即启动,并且永远不会停止,即使我点击它。计时器也向后(变成负数)而不是向前
有人能帮我理解我做错了什么吗?另外,我想知道这是否是一个好的计时器总体策略(使用timer.publish)
谢谢大家! 这里有一个固定版本。看看我所做的改变
如果计时器正在运行,则现在更新.onReceive
。时间字符串是现在(即timerString
)和Date()
之间的间隔startTime
- 如果计时器未运行,轻敲计时器可设置启动时间
上面的版本虽然简单,但却让我觉得
计时器一直在发布。我们只需要在计时器运行时发布计时器
以下是启动和停止计时器的版本:
struct TimerView: View {
@State var isTimerRunning = false
@State private var startTime = Date()
@State private var timerString = "0.00"
@State private var timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
var body: some View {
Text(self.timerString)
.font(Font.system(.largeTitle, design: .monospaced))
.onReceive(timer) { _ in
if self.isTimerRunning {
timerString = String(format: "%.2f", (Date().timeIntervalSince( self.startTime)))
}
}
.onTapGesture {
if isTimerRunning {
// stop UI updates
self.stopTimer()
} else {
timerString = "0.00"
startTime = Date()
// start UI updates
self.startTimer()
}
isTimerRunning.toggle()
}
.onAppear() {
// no need for UI updates at startup
self.stopTimer()
}
}
func stopTimer() {
self.timer.upstream.connect().cancel()
}
func startTimer() {
self.timer = Timer.publish(every: 0.01, on: .main, in: .common).autoconnect()
}
}
非常感谢。这很有效。我刚刚开始学习SwiftUI(和Swift),这段代码已经帮助我掌握了一些概念。现在我只需要从ContentView中找出如何使用时间
struct TimerView: View {
@State var isTimerRunning = false
@State private var startTime = Date()
@State private var timerString = "0.00"
@State private var timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
var body: some View {
Text(self.timerString)
.font(Font.system(.largeTitle, design: .monospaced))
.onReceive(timer) { _ in
if self.isTimerRunning {
timerString = String(format: "%.2f", (Date().timeIntervalSince( self.startTime)))
}
}
.onTapGesture {
if isTimerRunning {
// stop UI updates
self.stopTimer()
} else {
timerString = "0.00"
startTime = Date()
// start UI updates
self.startTimer()
}
isTimerRunning.toggle()
}
.onAppear() {
// no need for UI updates at startup
self.stopTimer()
}
}
func stopTimer() {
self.timer.upstream.connect().cancel()
}
func startTimer() {
self.timer = Timer.publish(every: 0.01, on: .main, in: .common).autoconnect()
}
}