Swift 根据时间戳显示时间或日期

Question

我有一个 API 可以返回包含该记录的时间戳的数据。 在 swift 中，我加载了时间戳元素并将其转换为 double ，然后可以将其转换为时间。如果记录的日期是今天，我希望能够返回时间；如果记录不是今天，我希望能够返回日期。 见下文:

        let unixTimeString:Double = Double(rowData["Timestamp"] as! String)!
        let date = NSDate(timeIntervalSince1970: unixTimeString) // This is on EST time and has not yet been localised.
        var dateFormatter = NSDateFormatter()
        dateFormatter.timeStyle = .ShortStyle
        dateFormatter.doesRelativeDateFormatting = true
        // If the date is today then just display the time, if the date is not today display the date and change the text color to grey.
        var stringTimestampResponse = dateFormatter.stringFromDate(date)
        cell.timestampLabel.text = String(stringTimestampResponse)

我是否使用 NSCalendar 来查看“日期”是否为今天，然后再做些什么？ 然后，您如何本地化时间，使其对用户而不是服务器时间正确？

Answer 1

NSCalendar 上有一个方便的函数可以告诉您 NSDate 是否在今天(至少需要 iOS 8)isDateInToday()

要查看它是否正常工作，请将它放到 playground 中:

// Create a couple of unix dates.
let timeIntervalToday: NSTimeInterval = NSDate().timeIntervalSince1970
let timeIntervalLastYear: NSTimeInterval = 1438435830


// This is just to show what the dates are.
let now = NSDate(timeIntervalSince1970: timeIntervalToday)
let then = NSDate(timeIntervalSince1970: timeIntervalLastYear)

// This is the function to show a formatted date from the timestamp
func displayTimestamp(ts: Double) -> String {
    let date = NSDate(timeIntervalSince1970: ts)
    let formatter = NSDateFormatter()
    formatter.timeZone = NSTimeZone.systemTimeZone()

    if NSCalendar.currentCalendar().isDateInToday(date) {
        formatter.dateStyle = .NoStyle
        formatter.timeStyle = .ShortStyle
    } else {
        formatter.dateStyle = .ShortStyle
        formatter.timeStyle = .NoStyle
    }

    return formatter.stringFromDate(date)
}

// This should just show the time.
displayTimestamp(timeIntervalToday)

// This should just show the date.
displayTimestamp(timeIntervalLastYear)

或者，如果您只是想看看它是什么样子而不自己运行它: