//截止日期let endDate = datePicker.date//开始日期let startDate = Date()//时间间隔let timeInterval:TimeInterval = endDate.timeIntervalSince(startDate)if timer == nil {
//剩余时间 var timeout = timeInterval if timeout != 0 {
//创建全局队列 let queue = DispatchQueue.global() //在全局队列下创建一个时间源 timer = DispatchSource.makeTimerSource(flags: [], queue: queue) //设定循环的间隔是一秒,并且立即开始 timer?.scheduleRepeating(wallDeadline: DispatchWallTime.now(), interval: .seconds(1)) //时间源出发事件 timer?.setEventHandler(handler: {
//必须是当前日期往后的日期,在datePicker上也做了限制 if timeout <= 0 {
self.timer?.cancel() self.timer = nil DispatchQueue.main.async(execute: {
self.day.text = "00" self.hour.text = "00" self.minute.text = "00" self.second.text = "00" }
) }
else {
//计算剩余时间 let days = Int(timeout) / (3600 * 24) if days == 0 {
self.day.text = "" }
let hours = (Int(timeout) - Int(days) * 24 * 3600) / 3600 let minutes = (Int(timeout) - Int(days) * 24 * 3600 - Int(hours) * 3600) / 60 let seconds = Int(timeout) - Int(days) * 24 * 3600 - Int(hours) * 3600 - Int(minutes) * 60 //主队列中刷新UI DispatchQueue.main.async(execute: {
if days == 0 {
self.day.text = "0" }
else {
self.day.text = "(days)" }
if hours < 10 {
self.hour.text = "0" + "(hours)" }
else {
self.hour.text = "(hours)" }
if minutes < 10 {
self.minute.text = "0" + "(minutes)" }
else {
self.minute.text = "(minutes)" }
if seconds < 10 {
self.second.text = "0" + "(seconds)" }
else {
self.second.text = "(seconds)" }
}
) timeout -= 1 }
}
) //启动时间源 timer?.resume() }
}