Display time in local timezone (e.g. New York timezone)

[pranavladkat]

When using utc timestamp for denoting time in CandlestickData and/or HistogramData, how can I display time in specific time zone (e.g. new york time zone or pacific time zone)? By default, it displays time zone in UTC.

[Mr-Alirezaa]

Hi @pranavladkat, hope this isn't too late.

You should pass a TimeScaleOptions to the LightweightChart, that defines a tickMarkFormatter. Like below:

let timeScaleOptions = TimeScaleOptions(
    visible: true,
    timeVisible: true,
    ticksVisible: true,
    tickMarkFormatter: .closure { parameters in
        switch parameters.tickMarkType {
        case .year:
            parameters.time.date
                .formatted(.dateTime.year(.relatedGregorian()))
        case .month:
            parameters.time.date
                .formatted(.dateTime.month(.twoDigits).year(.twoDigits))
        case .dayOfMonth:
            parameters.time.date
                .formatted(.dateTime.day(.twoDigits).month(.twoDigits))
        case .time:
            parameters.time.date
                .formatted(
                    .verbatim(
                        "\(hour: .twoDigits(clock: .twentyFourHour, hourCycle: .zeroBased)):\(minute: .twoDigits)",
                        timeZone: .current,
                        calendar: .current
                    )
                )
        case .timeWithSeconds:
            parameters.time.date
                .formatted(
                    .verbatim(
                        "\(hour: .twoDigits(clock: .twentyFourHour, hourCycle: .zeroBased)):\(minute: .twoDigits):\(second: .twoDigits)",
                        timeZone: .current,
                        calendar: .current
                    )
                )

        }
    }
)

Note that if you want to have granular access to customize your output date, you may use Date.VerbatimFormatStyle. Read more at this link. (Sorry for the language)

Now, you make the chart like following:

LightweightCharts(
    options: ChartOptions(
        // other parameters
        timeScale: timeScaleOptions,
        // ...
    )
)

Be aware that the date in parameters.time.date is an extension I wrote as below:

fileprivate extension EventTime {
    var date: Date {
        switch self {
        case let .utc(timestamp):
            return Date(timeIntervalSince1970: timestamp)

        case let .businessDay(businessDay):
            let dateComponent = DateComponents(
                timeZone: .gmt,
                year: businessDay.year,
                month: businessDay.month,
                day: businessDay.day
            )

            return Calendar.current.date(from: dateComponent)!

        case let .businessDayString(string):
            let components = string.components(separatedBy: "-").compactMap { Int($0) }
            let dateComponent = DateComponents(
                timeZone: .gmt,
                year: components[0],
                month: components[1],
                day: components[2]
            )

            return Calendar.current.date(from: dateComponent)!
        }
    }
}