ios - 秒表 iOS Swift

Question

我正在编写一个用于计时的秒表应用程序，我需要检查时钟是否超过某个时间间隔(例如 20:00 - 06:00)，在这种情况下，将当前耗时添加到我设置的 TimeInterval 变量中稍后将存储在数据库中。关于如何实现这一目标的任何想法？到目前为止，我已经尝试在滴答功能中检查它，但是当应用程序处于后台时它不会添加时间。

    import Foundation
    import os.log

/// The class protocol for a Stopwatch instance.
protocol StopwatchDelegate: class {
    func currentTimerUpdated(seconds: String, minutes: String, hours: String)
    func timerHasStarted()
    func timerHasStopped()
    func timerWasReset()
}

/// A container for a stopwatch.
class Stopwatch{

    //var currentTimerSession = [TimerSession] = []

    // *****************************************************************
    // MARK: - Stopwatch Properties
    // *****************************************************************

    /// The middleman for communicating with the view controller.
    weak var delegate: StopwatchDelegate?

    /// The actual Timer for this stopwatch.
    private(set) var timer: Timer?

    /// The time at which the timer was started.
    private(set) var timerStartTime: TimeInterval = 0

    /// The Timer-time at which the last user *pause* occurred.
    private(set) var timerSavedTime: TimeInterval = 0

    private(set) var timerSession = false

    // *****************************************************************
    // MARK: - Stopwatch Class Methods
    // *****************************************************************
    /// Create a new Stopwatch by locating the middleman and starting the timer.
    ///
    /// - Parameter delegate: the middleman to communicate to the view controller.
    /// - Returns: An instance to a ticking `Stopwatch`.
    ///
    init(delegate: StopwatchDelegate) {
        os_log("Initilzing timer.", log: OSLog.default, type: .debug)
        self.delegate = delegate
    }

    // *****************************************************************
    // MARK: - Stopwatch Timer Methods
    // ***************************************************************** *****************************************************************

    /// Start the stopwatch's timer.
    func startTimer() {
        timer = Timer.scheduledTimer(timeInterval: 0.01, target: self,
                                     selector: #selector(timerHasTicked(timer:)),
                                     userInfo: nil, repeats: true)
        RunLoop.current.add(timer!, forMode: RunLoopMode.commonModes)

        /// Record the time at which we started this timer.
        //checkForOngoingTimer()
        timerStartTime = Date.timeIntervalSinceReferenceDate

         timerOriginalStartTime = Date()
         timerSession = true


        delegate?.timerHasStarted()
    }

    /// Pause the Timer
    func stopTimer() {
        /// Save the Time delta of the current Timer.
        let currentTime = Date.timeIntervalSinceReferenceDate
        timerSavedTime += currentTime - timerStartTime
        timer?.invalidate()
        delegate?.timerHasStopped()
    }

    /// Reset the Timer and all of the laps.
    func resetTimer() {
        timerSavedTime = 0
        timerStartTime = 0
        timerSession = false

        timer?.invalidate()
        delegate?.timerWasReset()
    }

    /// Compute the new time values time values:
    ///
    /// - `minutes`: starts at 0 and increments to 59
    /// - `seconds`: starts at 0 and increments to 59
    /// - `hours`: starts at 0 and increments to 59
    ///
    /// - Parameter timer: The instance of the currently *running* Timer.
    ///
    @objc private func timerHasTicked(timer: Timer) {

        /// Find the time delta between start time and now.
        let currentTime = Date.timeIntervalSinceReferenceDate
        let timerElapsedTime: TimeInterval = (currentTime - timerStartTime) + timerSavedTime

        /// Convert elapsed time to minutes, seconds, and hours.
        let minutes = Int(timerElapsedTime) / 60 % 60
        let seconds = Int(timerElapsedTime) % 60
        let hours = Int(timerElapsedTime / 3600)

        let formatter = DateFormatter()
        formatter.timeZone = TimeZone.current
        formatter.dateFormat = "yyyy-MM-dd HH:mm"
        timerOriginalStartTime = formatter.string(from: timerOriginalStartTime)

        /// Let the delegate know the Time has been updated.
        delegate?.currentTimerUpdated(seconds: String(format: "%02u", seconds),
                                      minutes: String(format: "%02u", minutes),
                                      hours: String(format: "%02u", hours))
    }
    }

Answer 1

你的计时器不会在后台触发，所以最好的方法是在你启动秒表时存储开始时间，然后当应用程序进入后台并再次返回时，你可以计算当前与开始时间的偏移量。

如果你想支持暂停计时器，你可以跟踪暂停的开始和停止时间，并从总时间中减去它。