如何快速倒计时？

Question

我是 Swift 新手，还没有使用过 NSDate。对于我的应用程序，我需要如何计算距离活动还有多少天。事件的日期是用 Firebase 上的 DatePicker 编写的，我需要从当前日期计算距离编写日期还有多少天。我需要的只是倒计时。

Answer 1

将您的数据从 DatePicker 转换为 Date 对象，您可以使用以下函数返回 Int，表示已过日期的天数。

func daysTo(date: Date) -> Int? {
    let calendar = Calendar.current

    let date1 = calendar.startOfDay(for: Date())
    let date2 = calendar.startOfDay(for: date)

    let components = calendar.dateComponents([.day], from: date1, to: date2)
    return components.day
}

Answer 2

您可以使用此扩展来查找日期之间的差异：

extension Date {
    
    public func diffrenceTime() -> (Int, Int) {
        var cal = Calendar.init(identifier: .persian)
        let d1 = Date()
        let components = cal.dateComponents([.hour, .minute], from: self, to: d1)
        let diffHour = components.hour!
        let diffMinute = components.minute!
        
        return (diffHour, diffMinute)
    }
    
    public func fullDistance(from date: Date, resultIn component: Calendar.Component, calendar: Calendar = .current) -> Int? {
        calendar.dateComponents([component], from: self, to: date).value(for: component)
    }

    public func distance(from date: Date, only component: Calendar.Component, calendar: Calendar = .current) -> Int {
        let days1 = calendar.component(component, from: self)
        let days2 = calendar.component(component, from: date)
        return days1 - days2
    }

    public func hasSame(_ component: Calendar.Component, as date: Date) -> Bool {
        self.distance(from: date, only: component) == 0
    }
}

使用示例：

let dateOne = Date() // or any date
            let dateTwo = getDateFromServer // your second date for
            
            // option One
            let distanceDay = dateOne.fullDistance(from: dateTwo, resultIn: .day)
            
            var cal = Calendar.current // for your calendar
            cal.locale = Locale.init(identifier: "EN")
            // option Two
            let distanceDay = dateOne.fullDistance(from: dateTwo, resultIn: .day, calendar: cal)

您可以在结果参数中设置小时、分钟或任何组件来查找差异而不是天