NSDateFormatter。快速设置自日期以来经过的时间

Question

我希望调用一个函数来检查自日期以来经过的时间。这将决定 timeLable 在我的消息视图控制器中的显示方式，类似于 IMessage。

我在下面使用的代码只显示 HH:MM

let date = dateFormatter().dateFromString((recent["date"] as? String)!)

timeLabel.text = NSDateFormatter.localizedStringFromDate(date!, dateStyle: NSDateFormatterStyle.NoStyle, timeStyle: NSDateFormatterStyle.NoStyle)

我希望将其更改为以下内容：

• 如果日期是今天，则 date = "HH:MM"
• 如果日期是昨天，则 date = "昨天"
• 如果 date 是前天等，则 date = "Monday, Tuesday, Wednesday..."
• 如果日期超过 1 周，则日期 = MM/DD/YY

Answer 1

或者试试这个。请注意，我们必须使用components:fromDate:，然后使用components:fromDateComponents:toDateComponents:options:，因为如果我们不使用昨晚的 23:59，则会返回 23:59 而不是昨天。

extension NSDateFormatter {
    static func friendlyStringForDate(date:NSDate) -> String {
        // Fetch the default calendar
        let calendar = NSCalendar.currentCalendar()

        // Compute components from target date
        let from = calendar.components([.Day, .Month, .Year], fromDate: date)

        // Compute components from current date
        let to = calendar.components([.Day, .Month, .Year], fromDate: NSDate())

        // Compute days difference between the two
        let delta = calendar.components(.Day, fromDateComponents: from, toDateComponents: to, options: [])

        switch delta.day {
        case 0:
            let formatter = NSDateFormatter()
            formatter.timeZone = NSTimeZone.defaultTimeZone()
            formatter.dateFormat = "HH:mm"
            return formatter.stringFromDate(date)

        case 1:
            return "Yesterday"

        case 2..<7:
            let formatter = NSDateFormatter()
            formatter.timeStyle = .NoStyle
            formatter.dateFormat = "EEEE"
            return formatter.stringFromDate(date)

        default:
            let formatter = NSDateFormatter()
            formatter.timeStyle = .NoStyle
             formatter.dateFormat = "MM/dd/YY"
            return formatter.stringFromDate(date)
        }
    }
}

那么，就用它吧：

timeLabel.text = NSDateFormatter.friendlyStringForDate(date!)

Answer 2

SWIFT 3：

extension DateFormatter {

    static func friendlyStringForDate(date: Date) -> String {
        // Fetch the default calendar
        let calendar = Calendar.current
        let unitFlags: NSCalendar.Unit = [.day]

        // Compute days difference between the two
        let delta = (calendar as NSCalendar).components(unitFlags, from: date, to: Date(), options: [])

        if let day = delta.day {

            switch day {
            case 0:
                let formatter = DateFormatter()
                formatter.timeZone = NSTimeZone.default
                formatter.dateFormat = "hh:mm a"
                return formatter.string(from: date)

            case 1:
                return "Yesterday"

            case 2..<7:
                let formatter = DateFormatter()
                formatter.timeStyle = .none
                formatter.dateFormat = "EEEE"
                return formatter.string(from: date)

            default:
                let formatter = DateFormatter()
                formatter.timeStyle = .none
                formatter.dateFormat = "MM/dd/YY"
                return formatter.string(from: date)
            }
        }
        return ""
    }
}