如何从 iOS swift 中的日期获取 1 小时前？
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【中文标题】如何从 iOS swift 中的日期获取 1 小时前？【英文标题】：How to get 1 hour ago from a date in iOS swift? 【发布时间】：2014-12-02 14:19:23 【问题描述】：我一直在研究，但我找不到我的问题的确切解决方案。我一直试图从一个日期开始 1 小时前。我怎样才能快速做到这一点？
【问题讨论】：
【参考方案1】：对于涉及 NSDate 的正确计算，考虑到不同日历的所有边缘情况（例如在夏令时之间切换），您应该使用 NSCalendar 类：
Swift 3+
let earlyDate = Calendar.current.date(
byAdding: .hour,
value: -1,
to: Date())
老年人
// Get the date that was 1hr before now
let earlyDate = NSCalendar.currentCalendar().dateByAddingUnit(
.Hour,
value: -1,
toDate: NSDate(),
options: [])
【讨论】：
WrapComponents 有什么用？.WrapComponents 表示如果增加一个小时会使您超过午夜，则不要增加日期。我认为使用options: [] 更有意义，就像线程底部的 Deepak 的回答一样。
对于 Swift3 ... let changedDate = userCalendar.date(byAdding: .hour, value: -1, to: now)【参考方案2】：
使用此方法并粘贴到您的助手类中。
为 Swift 3 和 Xcode 8.3 更新
class func timeAgoSinceDate(_ date:Date,currentDate:Date, numericDates:Bool) -> String
let calendar = Calendar.current
let now = currentDate
let earliest = (now as NSDate).earlierDate(date)
let latest = (earliest == now) ? date : now
let components:DateComponents = (calendar as NSCalendar).components([NSCalendar.Unit.minute , NSCalendar.Unit.hour , NSCalendar.Unit.day , NSCalendar.Unit.weekOfYear , NSCalendar.Unit.month , NSCalendar.Unit.year , NSCalendar.Unit.second], from: earliest, to: latest, options: NSCalendar.Options())
if (components.year! >= 2)
return "\(components.year!) years ago"
else if (components.year! >= 1)
if (numericDates)
return "1 year ago"
else
return "Last year"
else if (components.month! >= 2)
return "\(components.month!) months ago"
else if (components.month! >= 1)
if (numericDates)
return "1 month ago"
else
return "Last month"
else if (components.weekOfYear! >= 2)
return "\(components.weekOfYear!) weeks ago"
else if (components.weekOfYear! >= 1)
if (numericDates)
return "1 week ago"
else
return "Last week"
else if (components.day! >= 2)
return "\(components.day!) days ago"
else if (components.day! >= 1)
if (numericDates)
return "1 day ago"
else
return "Yesterday"
else if (components.hour! >= 2)
return "\(components.hour!) hours ago"
else if (components.hour! >= 1)
if (numericDates)
return "1 hour ago"
else
return "An hour ago"
else if (components.minute! >= 2)
return "\(components.minute!) minutes ago"
else if (components.minute! >= 1)
if (numericDates)
return "1 minute ago"
else
return "A minute ago"
else if (components.second! >= 3)
return "\(components.second!) seconds ago"
else
return "Just now"
此方法的使用：
var timeAgo:String=AppHelper.timeAgoSinceDate(date, numericDates: true)
Print("\(timeAgo)") // Ex- 1 hour ago
【讨论】：
非常感谢，真的很有用！ 非常有用的答案！ 这里是 NSDate 类的扩展：gist.github.com/vikdenic/988d6f3920b7b7950d40 关于真正的 Swift 3(+) 摆脱NS... 类的建议：let earliest = min(now, date) – let latest = max(now, date) – let components = calendar.dateComponents([.minute , .hour , .day , .weekOfYear , .month , .year , .second], from: earliest, to: latest)
非常感谢.... :) 这个功能对我真的很有用【参考方案3】：
请阅读NSDate 类参考。
let oneHourAgo = NSDate.dateWithTimeIntervalSinceNow(-3600)
应该这样做。
或者，对于任何NSDate 对象：
let oneHourBack = myDate.dateByAddingTimeInterval(-3600)
斯威夫特 4：
let oneHourAgo = NSDate(timeIntervalSinceNow: -3600)
【讨论】：
感谢您的回答。问题消失了:) 前者的新语法为：NSDate(timeIntervalSinceNow: -3600)【参考方案4】：
根据您的需要，您可以选择以下 3 种 Swift 5 方法之一从 Date 实例获取一小时前。
1。 date(byAdding:value:to:wrappingComponents:)
Calendar 有一个名为date(byAdding:value:to:wrappingComponents:) 的方法。 date(byAdding:value:to:wrappingComponents:) 有以下声明：
func date(byAdding component: Calendar.Component, value: Int, to date: Date, wrappingComponents: Bool = default) -> Date?
返回一个新的
Date，表示通过将特定组件的数量与给定日期相加计算得出的日期。
下面的 Playground 代码显示了如何使用它：
import Foundation
let now = Date()
let oneHourAgo = Calendar.current.date(byAdding: .hour, value: -1, to: now)
print(now) // 2016-12-19 21:52:04 +0000
print(String(describing: oneHourAgo)) // Optional(2016-12-19 20:52:04 +0000)
2。 date(byAdding:to:wrappingComponents:)
Calendar 有一个名为date(byAdding:to:wrappingComponents:) 的方法。 date(byAdding:value:to:wrappingComponents:) 有以下声明：
func date(byAdding components: DateComponents, to date: Date, wrappingComponents: Bool = default) -> Date?
返回一个新的
Date，表示通过将组件添加到给定日期计算得出的日期。
下面的 Playground 代码显示了如何使用它：
import Foundation
let now = Date()
var components = DateComponents()
components.hour = -1
let oneHourAgo = Calendar.current.date(byAdding: components, to: now)
print(now) // 2016-12-19 21:52:04 +0000
print(String(describing: oneHourAgo)) // Optional(2016-12-19 20:52:04 +0000)
替代方案：
import Foundation
// Get the date that was 1hr before now
let now = Date()
let components = DateComponents(hour: -1)
let oneHourAgo = Calendar.current.date(byAdding: components, to: now)
print(now) // 2016-12-19 21:52:04 +0000
print(String(describing: oneHourAgo)) // Optional(2016-12-19 20:52:04 +0000)
3。 addingTimeInterval(_:)（慎用）
Date 有一个名为addingTimeInterval(_:) 的方法。 addingTimeInterval(_:) 有以下声明：
func addingTimeInterval(_ timeInterval: TimeInterval) -> Date
通过将
TimeInterval添加到此Date来返回新的Date。
请注意，此方法带有警告：
这只会调整绝对值。如果您想添加诸如小时、天、月之类的日历概念，则必须使用
Calendar。这将考虑到复杂性，例如夏令时、不同天数的月份等等。
下面的 Playground 代码显示了如何使用它：
import Foundation
let now = Date()
let oneHourAgo = now.addingTimeInterval(-3600)
print(now) // 2016-12-19 21:52:04 +0000
print(oneHourAgo) // 2016-12-19 20:52:04 +0000
【讨论】：
选项一，date(byAdding:value:to:wrappingComponents:) 似乎是最合适/最简单的选择。它允许您将单个日期组件值添加到日期。【参考方案5】：
如果你使用NSDate，你可以这样做：
let date = NSDate()
date.dateByAddingTimeInterval(-3600)
它将date 对象更改为“1 小时前”。
【讨论】：
【参考方案6】：Swift3：
let now = Date()
let tempCalendar = Calendar.current
let alteredDate = tempCalendar.date(byAdding: .hour, value: -1, to: now)
【讨论】：
【参考方案7】：我通过创建 Date 的扩展来实现时间前的功能。如下：
extension Date
// Returns the number of years
func yearsCount(from date: Date) -> Int
return Calendar.current.dateComponents([.year], from: date, to: self).year ?? 0
// Returns the number of months
func monthsCount(from date: Date) -> Int
return Calendar.current.dateComponents([.month], from: date, to: self).month ?? 0
// Returns the number of weeks
func weeksCount(from date: Date) -> Int
return Calendar.current.dateComponents([.weekOfMonth], from: date, to: self).weekOfMonth ?? 0
// Returns the number of days
func daysCount(from date: Date) -> Int
return Calendar.current.dateComponents([.day], from: date, to: self).day ?? 0
// Returns the number of hours
func hoursCount(from date: Date) -> Int
return Calendar.current.dateComponents([.hour], from: date, to: self).hour ?? 0
// Returns the number of minutes
func minutesCount(from date: Date) -> Int
return Calendar.current.dateComponents([.minute], from: date, to: self).minute ?? 0
// Returns the number of seconds
func secondsCount(from date: Date) -> Int
return Calendar.current.dateComponents([.second], from: date, to: self).second ?? 0
// Returns time ago by checking if the time differences between two dates are in year or months or weeks or days or hours or minutes or seconds
func timeAgo(from date: Date) -> String
if yearsCount(from: date) > 0 return "\(yearsCount(from: date))years ago"
if monthsCount(from: date) > 0 return "\(monthsCount(from: date))months ago"
if weeksCount(from: date) > 0 return "\(weeksCount(from: date))weeks ago"
if daysCount(from: date) > 0 return "\(daysCount(from: date))days ago"
if hoursCount(from: date) > 0 return "\(hoursCount(from: date))hours ago"
if minutesCount(from: date) > 0 return "\(minutesCount(from: date))minutes ago"
if secondsCount(from: date) > 0 return "\(secondsCount(from: date))seconds ago"
return ""
然后我通过计算当前日期和指定日期之间的差异来获得时间：
let timeAgo = Date().timeAgo(from: sender.date)
【讨论】：
【参考方案8】：对于 Swift 2：
extension NSDate
func after(value: Int, calendarUnit:NSCalendarUnit) -> NSDate
return calendar.dateByAddingUnit(calendarUnit, value: value, toDate: self, options: [])!
使用方法：
let lastHour = NSDate().after(-1, calendarUnit: .Hour)
【讨论】：
【参考方案9】：你也可以使用运算符
let date = Date()
let anHourAgo = date - TimeInterval(3600.0)
苹果文档： https://developer.apple.com/documentation/foundation/date/2293436
【讨论】：
【参考方案10】：这适用于 ios 13 / Swift 5。感谢 Sourabh Sharma
func timeAgoSinceNow(numericDates: Bool = true) -> String
let calendar = Calendar.current
let now = Date()
let earliest = (now as NSDate).earlierDate(self)
let latest = (earliest == now) ? self : now
let components: DateComponents = (calendar as NSCalendar).components([NSCalendar.Unit.minute,
NSCalendar.Unit.hour,
NSCalendar.Unit.day,
NSCalendar.Unit.weekOfYear,
NSCalendar.Unit.month,
NSCalendar.Unit.year,
NSCalendar.Unit.second],
from: earliest,
to: latest,
options: NSCalendar.Options())
guard
let year = components.year,
let month = components.month,
let weekOfYear = components.weekOfYear,
let day = components.day,
let hour = components.hour,
let minute = components.minute,
let second = components.second
else return "A while ago"
if year >= 1
return year >= 2 ? "\(year) years ago" : numericDates ? "1 year ago" : "Last year"
else if month >= 1
return month >= 2 ? "\(month) months ago" : numericDates ? "1 month ago" : "Last month"
else if weekOfYear >= 1
return weekOfYear >= 2 ? "\(weekOfYear) weeks ago" : numericDates ? "1 week ago" : "Last week"
else if day >= 1
return day >= 2 ? "\(day) days ago" : numericDates ? "1 day ago" : "Yesterday"
else if hour >= 1
return hour >= 2 ? "\(hour) hours ago" : numericDates ? "1 hour ago" : "An hour ago"
else if minute >= 1
return minute >= 2 ? "\(minute) minutes ago" : numericDates ? "1 minute ago" : "A minute ago"
else
return second >= 3 ? "\(second) seconds ago" : "Just now"
用法：
var date = Date() // Or any date you wish to convert to text
print("\(date.timeAgoSinceNow())") // "Just Now"
【讨论】：
【参考方案11】：Calendar.current.date( byAdding: .hour, value: -1, to: Date())
【讨论】：
请考虑将答案的相关部分格式化为代码。 它看起来对之前提供的其他答案没有任何改进【参考方案12】：在swift 5中你可以使用
let earlyDate = Calendar.current.date( byAdding: .hour, value: -1, to: Date())
let df = DateFormatter()
df.dateFormat = "yyyy-MM-dd HH:mm:ss"
let dateString = df.string(from: earlyDate!)
输出会像下面这样
Current DateTime--> 2019-12-20 09:40:08
One Hour Previous Date Time--> 2019-12-20 08:40:08
【讨论】：
【参考方案13】：详情
Xcode 11.4 (11E146)、Swift 5.2解决方案
import Foundation
extension Date
typealias Component = (value: Int, type: Calendar.Component)
init?(bySubtracting components: Component..., calendar: Calendar = Calendar.current, from date: Date)
guard let date = date.subtract(components, calendar: calendar) else return nil
self = date
func subtract(_ components: Component..., calendar: Calendar = Calendar.current) -> Date?
subtract(components, calendar: calendar)
func subtract(_ components: [Component], calendar: Calendar = Calendar.current) -> Date?
components.reduce(self) (result, component) -> Date? in
guard let date = result else return nil
return calendar.date(byAdding: component.type, value: (-1)*component.value, to: date)
static func beforeNow(difference component: Component..., calendar: Calendar = Calendar.current) -> Date?
Date().subtract(component, calendar: calendar)
static func beforeNow(difference component: [Component], calendar: Calendar = Calendar.current) -> Date?
Date().subtract(component, calendar: calendar)
extension Date
static func - (date: Date, component: Date.Component) -> Date? date.subtract(component, calendar: Calendar.current)
static func -= (date: inout Date, component: Date.Component)
guard let newDate = date.subtract(component, calendar: Calendar.current) else return
date = newDate
用法
var currentDate = Date()
let date1 = Date(bySubtracting: (30, .day), from: currentDate)
let date2 = Date().subtract((30, .day))
let date3 = Date().subtract([(1, .minute), (2, .hour), (3, .day), (4, .month)])
let component = Date.Component(value: 1, type: .day)
let date4 = Date.beforeNow(difference: component)
let date5 = Date.beforeNow(difference: (1, .minute), (2, .hour), (3, .day), (4, .month))
let date6 = Date.beforeNow(difference: [(1, .minute), (2, .hour), (3, .day), (4, .month)])
let date7 = currentDate - (1, .day)
currentDate -= Date.Component(value: 1, type: .day)
更多
Get components (hours, months, days...) from date Compare days by components Convert date to formated string date【讨论】：
【参考方案14】：let now = Date()
let nowMinusTwoAndAHalfHours = now - 2.5*60*60
print(now)
print(nowMinusTwoAndAHalfHours)
【讨论】：
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