如何从iOS swift中的约会中获取1小时前的信息？

我一直在研究，但找不到解决问题的确切方法。我一直在试着在一个小时前从约会中恢复过来。如何在swift中实现这一点？

请阅读

NSDate

课程参考

let oneHourAgo = NSDate.dateWithTimeIntervalSinceNow(-3600)

我应该这样做

或者，对于任何

NSDate

对象：

let oneHourBack = myDate.dateByAddingTimeInterval(-3600)

Swift 4:

let oneHourAgo = NSDate(timeIntervalSinceNow: -3600)

var timeAgo:String=AppHelper.timeAgoSinceDate(date, numericDates: true)
Print("\(timeAgo)")   // Ex- 1 hour ago

---

要正确计算NSDate，并考虑不同日历的所有边缘情况（例如，在日间保存时间之间切换），应使用NSCalendar类：

Swift 3+

let earlyDate = Calendar.current.date(
  byAdding: .hour, 
  value: -1, 
  to: Date())

较老的

// Get the date that was 1hr before now
let earlyDate = NSCalendar.currentCalendar().dateByAddingUnit(
       .Hour,
       value: -1, 
       toDate: NSDate(),
       options: [])

---

如果您使用的是

NSDate

，您可以执行以下操作：

let date = NSDate()
date.dateByAddingTimeInterval(-3600)

---

它会将

日期

对象更改为“1小时前”。

使用此方法并粘贴到助手类中

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：

let oneHourAgo = NSDate(timeIntervalSinceNow: -3600)

var timeAgo:String=AppHelper.timeAgoSinceDate(date, numericDates: true)
Print("\(timeAgo)")   // Ex- 1 hour ago

对于Swift 2：

extension NSDate {
    func after(value: Int, calendarUnit:NSCalendarUnit) -> NSDate {
        return calendar.dateByAddingUnit(calendarUnit, value: value, toDate: self, options: [])!
    }
}

如何使用：

let lastHour = NSDate().after(-1, calendarUnit: .Hour)

---

根据您的需要，您可以从以下3种Swift 5方法中选择一种，从

Date

实例中提前一小时获取

---

1. <代码>日期（通过将：值：添加到：包装组件：）

Calendar

有一个名为的方法<代码>日期（通过添加：value:to:wrappingComponents:）具有以下声明：

func date(byAdding component: Calendar.Component, value: Int, to date: Date, wrappingComponents: Bool = default) -> Date?

func date(byAdding components: DateComponents, to date: Date, wrappingComponents: Bool = default) -> Date?

func addingTimeInterval(_ timeInterval: TimeInterval) -> Date

返回一个新的

日期

，该日期表示通过向给定日期添加特定组件的数量来计算的日期

下面的操场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)

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)

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

---

2. <代码>日期（通过将：添加到：包装组件：）

Calendar

有一个名为的方法<代码>日期（通过添加：value:to:wrappingComponents:）具有以下声明：

func date(byAdding component: Calendar.Component, value: Int, to date: Date, wrappingComponents: Bool = default) -> Date?

func date(byAdding components: DateComponents, to date: Date, wrappingComponents: Bool = default) -> Date?

func addingTimeInterval(_ timeInterval: TimeInterval) -> Date

返回新的

日期

，表示通过向给定日期添加组件计算的日期

下面的操场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)

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)

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

备选方案：

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. <代码>添加时间间隔（：）（小心使用）

Date

有一个名为的方法

addingTimeInterval（:）

具有以下声明：

func date(byAdding component: Calendar.Component, value: Int, to date: Date, wrappingComponents: Bool = default) -> Date?

func date(byAdding components: DateComponents, to date: Date, wrappingComponents: Bool = default) -> Date?

func addingTimeInterval(_ timeInterval: TimeInterval) -> Date

通过在此

日期

中添加

时间间隔

，返回新的

日期

请注意，此方法附带警告：

这只会调整绝对值。如果您希望添加日历概念，如小时、天、月，则必须使用

日历

。这将考虑到诸如夏令时、不同天数的月份等复杂性

下面的操场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)

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)

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

迅捷3：

let now = Date()
let tempCalendar = Calendar.current
let alteredDate = tempCalendar.date(byAdding: .hour, value: -1, to: now)

---

我通过创建日期扩展来实现“时间前”功能。具体如下：

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值来获得时间：

   let timeAgo = Date().timeAgo(from: sender.date)

---

也可以使用运算符

let date=date（）
设Anhorago=日期-时间间隔（3600.0）

苹果文档： 在swift 5中，您可以使用

      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!)

输出将像贝娄

Current DateTime--> 2019-12-20 09:40:08
One Hour Previous Date Time--> 2019-12-20 08:40:08

---

这适用于iOS 13/Swift 5。功劳归于

用法：

var date = Date() // Or any date you wish to convert to text
print("\(date.timeAgoSinceNow())") // "Just Now"

细节

• 代码11.4（11E146），Swift 5.2

解决方案 用法 更多

---

感谢您的回答。问题消失了：）前者的新语法是：

NSDate（timeIntervalSinceNow:-3600）

WrapComponents是做什么的？

。WrapComponents

意味着如果增加一个小时会使你超过午夜，那么就不要增加一天。我认为使用

选项更有意义：[]

，就像线程底部的Deepak答案一样。对于Swift3。。。让alteredDate=userCalendar.date（通过添加：.hour，value:-1，to:now）非常感谢，非常有用！非常有用的答案！这里它是NSDate类的扩展：real Swift 3（+）摆脱

NS…

类的建议：

让最早的=min（现在，日期）

–

让最晚的=max（现在，日期）

–

让组件=calendar.dateComponents（[.minute、.hour、.day、.weekOfYear、.month、.year、.second]，从：最早，到：最晚）

非常感谢……）这个函数对我来说非常有用。选项一，

date（通过添加：value:to:wrappingComponents:）

似乎是最合适/最简单的。它允许您向日期添加单个日期组件值。请考虑将您的答案的相关部分格式化为代码。