entityMap|blocks|key|2ch89|text|请阅读NSDate类引用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|7r1e7|let+oneHourAgo+=+NSDate.dateWithTimeIntervalSinceNow(-3600)|code-block|syntax|javascript|640cc|应该这么做。|cfj5r|或者，对于任何NSDate+对象：|8l794|let+oneHourBack+=+myDate.dateByAddingTimeInterval(-3600)|bm31o|Swift+4：|b4a5i|let+oneHourAgo+=+NSDate(timeIntervalSinceNow:+-3600)^0|3|6|0|0|0|7|7|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|V|9|@$A|W|B|X|C|D]]|E|@]|F|$]]|$2|G|4|H|6|I|8|Y|9|@]|E|@]|F|$J|K]]|$2|L|4|M|6|7|8|Z|9|@]|E|@]|F|$]]|$2|N|4|O|6|7|8|10|9|@$A|11|B|12|C|D]]|E|@]|F|$]]|$2|P|4|Q|6|I|8|13|9|@]|E|@]|F|$J|K]]|$2|R|4|S|6|7|8|14|9|@]|E|@]|F|$]]|$2|T|4|U|6|I|8|15|9|@]|E|@]|F|$J|K]]]]

Please read the <code>NSDate</code> class reference.

<pre><code>let oneHourAgo = NSDate.dateWithTimeIntervalSinceNow(-3600)
</code></pre>

should do it.

Or, for any <code>NSDate</code> object:

<pre><code>let oneHourBack = myDate.dateByAddingTimeInterval(-3600)
</code></pre>

Swift 4:

<pre><code>let oneHourAgo = NSDate(timeIntervalSinceNow: -3600)
</code></pre>

entityMap|blocks|key|fap9d|text|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：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5duuc|Swift+3%2B|4onss|let+earlyDate+=+Calendar.current.date(
++byAdding:+.hour,+
++value:+-1,+
++to:+Date())|code-block|syntax|javascript|2b8c8|更老的|9akpe|//+Get+the+date+that+was+1hr+before+now
let+earlyDate+=+NSCalendar.currentCalendar().dateByAddingUnit(
+++++++.Hour,
+++++++value:+-1,+
+++++++toDate:+NSDate(),
+++++++options:+[])^0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|N|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|O|9|@]|A|@]|B|$]]|$2|E|4|F|6|G|8|P|9|@]|A|@]|B|$H|I]]|$2|J|4|K|6|7|8|Q|9|@]|A|@]|B|$]]|$2|L|4|M|6|G|8|R|9|@]|A|@]|B|$H|I]]]]

For correct calculations involving NSDate that take into account all edge cases of different calendars (e.g. switching between day saving time) you should use NSCalendar class:

Swift 3+

<pre><code>let earlyDate = Calendar.current.date(
 byAdding: .hour, 
 value: -1, 
 to: Date())
</code></pre>

Older

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

entityMap|blocks|key|91m5d|text|如果您正在使用NSDate您可以执行以下操作：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|fl5dr|let+date+=+NSDate()
date.dateByAddingTimeInterval(-3600)|code-block|syntax|javascript|636ci|它将改变date+对象设置为"1小时前“。^0|7|6|0|0|4|5^^$0|$]|1|@$2|3|4|5|6|7|8|N|9|@$A|O|B|P|C|D]]|E|@]|F|$]]|$2|G|4|H|6|I|8|Q|9|@]|E|@]|F|$J|K]]|$2|L|4|M|6|7|8|R|9|@$A|S|B|T|C|D]]|E|@]|F|$]]]]

If you are using <code>NSDate</code> you can do:

<pre><code>let date = NSDate()
date.dateByAddingTimeInterval(-3600)
</code></pre>

It will change the <code>date</code> object to be "1 hour ago".

entityMap|blocks|key|4hm81|text|使用此方法并粘贴到您的帮助器类中。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|48j19|针对Swift+3和Xcode+8.3进行了更新|7532l|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"
++++}
++++
}|code-block|syntax|javascript|7t4jr|使用此方法：|dth6m|var+timeAgo:String=AppHelper.timeAgoSinceDate(date,+numericDates:+true)
Print("\(timeAgo)")+++//+Ex-+1+hour+ago^0|0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|N|9|@]|A|@]|B|$]]|$2|C|4|D|6|7|8|O|9|@]|A|@]|B|$]]|$2|E|4|F|6|G|8|P|9|@]|A|@]|B|$H|I]]|$2|J|4|K|6|7|8|Q|9|@]|A|@]|B|$]]|$2|L|4|M|6|G|8|R|9|@]|A|@]|B|$H|I]]]]

Use this method and paste in your helper class.
Updated for Swift 3 and Xcode 8.3
<pre><code>class func timeAgoSinceDate(_ date:Date,currentDate:Date, numericDates:Bool) -&gt; 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! &gt;= 2) {
 return &quot;\(components.year!) years ago&quot;
 } else if (components.year! &gt;= 1){
 if (numericDates){
 return &quot;1 year ago&quot;
 } else {
 return &quot;Last year&quot;
 }
 } else if (components.month! &gt;= 2) {
 return &quot;\(components.month!) months ago&quot;
 } else if (components.month! &gt;= 1){
 if (numericDates){
 return &quot;1 month ago&quot;
 } else {
 return &quot;Last month&quot;
 }
 } else if (components.weekOfYear! &gt;= 2) {
 return &quot;\(components.weekOfYear!) weeks ago&quot;
 } else if (components.weekOfYear! &gt;= 1){
 if (numericDates){
 return &quot;1 week ago&quot;
 } else {
 return &quot;Last week&quot;
 }
 } else if (components.day! &gt;= 2) {
 return &quot;\(components.day!) days ago&quot;
 } else if (components.day! &gt;= 1){
 if (numericDates){
 return &quot;1 day ago&quot;
 } else {
 return &quot;Yesterday&quot;
 }
 } else if (components.hour! &gt;= 2) {
 return &quot;\(components.hour!) hours ago&quot;
 } else if (components.hour! &gt;= 1){
 if (numericDates){
 return &quot;1 hour ago&quot;
 } else {
 return &quot;An hour ago&quot;
 }
 } else if (components.minute! &gt;= 2) {
 return &quot;\(components.minute!) minutes ago&quot;
 } else if (components.minute! &gt;= 1){
 if (numericDates){
 return &quot;1 minute ago&quot;
 } else {
 return &quot;A minute ago&quot;
 }
 } else if (components.second! &gt;= 3) {
 return &quot;\(components.second!) seconds ago&quot;
 } else {
 return &quot;Just now&quot;
 }
 
}
</code></pre>
Use of this method:
<pre><code>var timeAgo:String=AppHelper.timeAgoSinceDate(date, numericDates: true)
Print(&quot;\(timeAgo)&quot;) // Ex- 1 hour ago
</code></pre>

entityMap|blocks|key|a04m5|text|对于Swift+2：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|cmmq6|extension+NSDate+{
++++func+after(value:+Int,+calendarUnit:NSCalendarUnit)+->+NSDate+{
++++++++return+calendar.dateByAddingUnit(calendarUnit,+value:+value,+toDate:+self,+options:+[])!
++++}
}|code-block|syntax|javascript|6qbs0|使用方法：|fks87|let+lastHour+=+NSDate().after(-1,+calendarUnit:+.Hour)^0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|L|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|M|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|N|9|@]|A|@]|B|$]]|$2|J|4|K|6|E|8|O|9|@]|A|@]|B|$F|G]]]]

for Swift 2:

<pre><code>extension NSDate {
 func after(value: Int, calendarUnit:NSCalendarUnit) -&gt; NSDate {
 return calendar.dateByAddingUnit(calendarUnit, value: value, toDate: self, options: [])!
 }
}
</code></pre>

how to use:

<pre><code>let lastHour = NSDate().after(-1, calendarUnit: .Hour)
</code></pre>

entityMap|blocks|key|5ttro|text|根据您的需要，您可以从以下3种Swift+5方法中选择一种，以便在一小时前从Date|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5aj57|实例。|6nt5p|1.date(byAdding:value:to:wrappingComponents:)|9h4d8|Calendar有一个名为+date(byAdding:value:to:wrappingComponents:)。|61b85|date(byAdding:value:to:wrappingComponents:)具有以下声明：|8rmtr|func+date(byAdding+component:+Calendar.Component,+value:+Int,+to+date:+Date,+wrappingComponents:+Bool+=+default)+->+Date?|code-block|syntax|javascript|aj2bj|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而计算出的日期。|93cee|下面的Playground代码展示了如何使用它：|67ejr|import+Foundation

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

print(now)+//+2016-12-19+21:52:04+%2B0000
print(String(describing:+oneHourAgo))+//+Optional(2016-12-19+20:52:04+%2B0000)|7vh9c|2.date(byAdding:to:wrappingComponents:)|8lclv|Calendar有一个名为+date(byAdding:to:wrappingComponents:).+date(byAdding:value:to:wrappingComponents:)。|1q7pc|具有以下声明：|cb2i8|func+date(byAdding+components:+DateComponents,+to+date:+Date,+wrappingComponents:+Bool+=+default)+->+Date?|2oedd|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。|db211|6slcp|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+%2B0000
print(String(describing:+oneHourAgo))+//+Optional(2016-12-19+20:52:04+%2B0000)|8n5g6|替代方案：|fp9pt|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+%2B0000
print(String(describing:+oneHourAgo))+//+Optional(2016-12-19+20:52:04+%2B0000)|dfrln|3.addingTimeInterval(_:)(请谨慎使用)|36fhg|Date有一个名为+addingTimeInterval(_:).+addingTimeInterval(_:)。具有以下声明：|btv07|func+addingTimeInterval(_+timeInterval:+TimeInterval)+->+Date|87ftb|返回一个新的+Date通过添加一个TimeInterval到这个Date。|7p3tb|请注意，此方法附带一个警告：|9oaq|这只会调整绝对值。如果您希望添加诸如小时、天、月之类的日历概念，则必须使用Calendar。这将考虑到夏令时、不同天数的月份等复杂性。|d65o6|63raq|import+Foundation

let+now+=+Date()
let+oneHourAgo+=+now.addingTimeInterval(-3600)

print(now)+//+2016-12-19+21:52:04+%2B0000
print(oneHourAgo)+//+2016-12-19+20:52:04+%2B0000^0|12|4|0|0|2|17|0|0|8|D|18|0|0|17|0|0|6|4|0|0|0|2|11|0|0|8|D|2B|0|0|0|6|4|0|0|0|0|0|2|M|0|0|4|9|1B|0|0|6|5|H|C|W|4|0|0|11|8|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|1V|9|@$A|1W|B|1X|C|D]]|E|@]|F|$]]|$2|G|4|H|6|7|8|1Y|9|@]|E|@]|F|$]]|$2|I|4|J|6|7|8|1Z|9|@$A|20|B|21|C|D]]|E|@]|F|$]]|$2|K|4|L|6|7|8|22|9|@$A|23|B|24|C|D]|$A|25|B|26|C|D]]|E|@]|F|$]]|$2|M|4|N|6|7|8|27|9|@$A|28|B|29|C|D]]|E|@]|F|$]]|$2|O|4|P|6|Q|8|2A|9|@]|E|@]|F|$R|S]]|$2|T|4|U|6|7|8|2B|9|@$A|2C|B|2D|C|D]]|E|@]|F|$]]|$2|V|4|W|6|7|8|2E|9|@]|E|@]|F|$]]|$2|X|4|Y|6|Q|8|2F|9|@]|E|@]|F|$R|S]]|$2|Z|4|10|6|7|8|2G|9|@$A|2H|B|2I|C|D]]|E|@]|F|$]]|$2|11|4|12|6|7|8|2J|9|@$A|2K|B|2L|C|D]|$A|2M|B|2N|C|D]]|E|@]|F|$]]|$2|13|4|14|6|7|8|2O|9|@]|E|@]|F|$]]|$2|15|4|16|6|Q|8|2P|9|@]|E|@]|F|$R|S]]|$2|17|4|18|6|7|8|2Q|9|@$A|2R|B|2S|C|D]]|E|@]|F|$]]|$2|19|4|W|6|7|8|2T|9|@]|E|@]|F|$]]|$2|1A|4|1B|6|Q|8|2U|9|@]|E|@]|F|$R|S]]|$2|1C|4|1D|6|7|8|2V|9|@]|E|@]|F|$]]|$2|1E|4|1F|6|Q|8|2W|9|@]|E|@]|F|$R|S]]|$2|1G|4|1H|6|7|8|2X|9|@$A|2Y|B|2Z|C|D]]|E|@]|F|$]]|$2|1I|4|1J|6|7|8|30|9|@$A|31|B|32|C|D]|$A|33|B|34|C|D]]|E|@]|F|$]]|$2|1K|4|1L|6|Q|8|35|9|@]|E|@]|F|$R|S]]|$2|1M|4|1N|6|7|8|36|9|@$A|37|B|38|C|D]|$A|39|B|3A|C|D]|$A|3B|B|3C|C|D]]|E|@]|F|$]]|$2|1O|4|1P|6|7|8|3D|9|@]|E|@]|F|$]]|$2|1Q|4|1R|6|7|8|3E|9|@$A|3F|B|3G|C|D]]|E|@]|F|$]]|$2|1S|4|W|6|7|8|3H|9|@]|E|@]|F|$]]|$2|1T|4|1U|6|Q|8|3I|9|@]|E|@]|F|$R|S]]]]

According to your needs, you may choose one of the 3 following Swift 5 methods to get one hour ago from a <code>Date</code> instance.
<hr />
<h2>1. <code>date(byAdding:value:to:wrappingComponents:)</code></h2>
<code>Calendar</code> has a method called <a href="https://developer.apple.com/documentation/foundation/calendar/2293453-date" rel="noreferrer"><code>date(byAdding:value:to:wrappingComponents:)</code></a>. <code>date(byAdding:value:to:wrappingComponents:)</code> has the following declaration:
<pre><code>func date(byAdding component: Calendar.Component, value: Int, to date: Date, wrappingComponents: Bool = default) -&gt; Date?
</code></pre>
<blockquote>
Returns a new <code>Date</code> representing the date calculated by adding an amount of a specific component to a given date.
</blockquote>
The Playground code below shows how to use it:
<pre><code>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)
</code></pre>
<hr />
<h2>2. <code>date(byAdding:to:wrappingComponents:)</code></h2>
<code>Calendar</code> has a method called <a href="https://developer.apple.com/documentation/foundation/calendar/2293676-date" rel="noreferrer"><code>date(byAdding:to:wrappingComponents:)</code></a>. <code>date(byAdding:value:to:wrappingComponents:)</code> has the following declaration:
<pre><code>func date(byAdding components: DateComponents, to date: Date, wrappingComponents: Bool = default) -&gt; Date?
</code></pre>
<blockquote>
Returns a new <code>Date</code> representing the date calculated by adding components to a given date.
</blockquote>
The Playground code below shows how to use it:
<pre><code>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)
</code></pre>
Alternative:
<pre><code>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)
</code></pre>
<hr />
<h2>3. <code>addingTimeInterval(_:)</code> (use with caution)</h2>
<code>Date</code> has a method called <a href="https://developer.apple.com/documentation/foundation/date/1948745-addingtimeinterval" rel="noreferrer"><code>addingTimeInterval(_:)</code></a>. <code>addingTimeInterval(_:)</code> has the following declaration:
<pre><code>func addingTimeInterval(_ timeInterval: TimeInterval) -&gt; Date
</code></pre>
<blockquote>
Return a new <code>Date</code> by adding a <code>TimeInterval</code> to this <code>Date</code>.
</blockquote>
Note that this method comes with a warning:
<blockquote>
This only adjusts an absolute value. If you wish to add calendrical concepts like hours, days, months then you must use a <code>Calendar</code>. That will take into account complexities like daylight saving time, months with different numbers of days, and more.
</blockquote>
The Playground code below shows how to use it:
<pre><code>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
</code></pre>

entityMap|blocks|key|8ecnf|text|Swift3：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|fa1e1|let+now+=+Date()
let+tempCalendar+=+Calendar.current
let+alteredDate+=+tempCalendar.date(byAdding:+.hour,+value:+-1,+to:+now)|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

Swift3:

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

entityMap|blocks|key|8qiga|text|我通过创建日期的扩展来实现时间前的功能。如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|6bo5m|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+""
++}
}|code-block|syntax|javascript|dr385|然后，我通过计算当前日期和指定日期之间的差值来获得之前的时间：|cl010|let+timeAgo+=+Date().timeAgo(from:+sender.date)^0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|L|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|M|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|N|9|@]|A|@]|B|$]]|$2|J|4|K|6|E|8|O|9|@]|A|@]|B|$F|G]]]]

I achieve time ago functionality by creating extension of Date. Which is given below:

<pre><code>extension Date {
 // Returns the number of years 
 func yearsCount(from date: Date) -&gt; Int {
 return Calendar.current.dateComponents([.year], from: date, to: self).year ?? 0
 }
 // Returns the number of months
 func monthsCount(from date: Date) -&gt; Int {
 return Calendar.current.dateComponents([.month], from: date, to: self).month ?? 0
 }
 // Returns the number of weeks
 func weeksCount(from date: Date) -&gt; Int {
 return Calendar.current.dateComponents([.weekOfMonth], from: date, to: self).weekOfMonth ?? 0
 }
 // Returns the number of days
 func daysCount(from date: Date) -&gt; Int {
 return Calendar.current.dateComponents([.day], from: date, to: self).day ?? 0
 }
 // Returns the number of hours
 func hoursCount(from date: Date) -&gt; Int {
 return Calendar.current.dateComponents([.hour], from: date, to: self).hour ?? 0
 }
 // Returns the number of minutes
func minutesCount(from date: Date) -&gt; Int {
 return Calendar.current.dateComponents([.minute], from: date, to: self).minute ?? 0
 }
 // Returns the number of seconds
 func secondsCount(from date: Date) -&gt; 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) -&gt; String {
 if yearsCount(from: date) &gt; 0 { return "\(yearsCount(from: date))years ago" }
 if monthsCount(from: date) &gt; 0 { return "\(monthsCount(from: date))months ago" }
 if weeksCount(from: date) &gt; 0 { return "\(weeksCount(from: date))weeks ago" }
 if daysCount(from: date) &gt; 0 { return "\(daysCount(from: date))days ago" }
 if hoursCount(from: date) &gt; 0 { return "\(hoursCount(from: date))hours ago" }
 if minutesCount(from: date) &gt; 0 { return "\(minutesCount(from: date))minutes ago" }
 if secondsCount(from: date) &gt; 0 { return "\(secondsCount(from: date))seconds ago" }
 return ""
 }
}
</code></pre>

Then i get the time ago by calculating the difference between current date and specified date:

<pre><code> let timeAgo = Date().timeAgo(from: sender.date)
</code></pre>

entityMap|0|type|LINK|mutability|MUTABLE|data|url|https://developer.apple.com/documentation/foundation/date/2293436|blocks|key|ec0h1|text|您还可以使用运算符|unstyled|depth|inlineStyleRanges|entityRanges|6u6f6|let+date+=+Date()
let+anHourAgo+=+date+-+TimeInterval(3600.0)|code-block|syntax|javascript|50o4b|Apple+Docs：https://developer.apple.com/documentation/foundation/date/2293436|offset|length^0|0|0|B|1T|0^^$0|$1|$2|3|4|5|6|$7|8]]]|9|@$A|B|C|D|2|E|F|R|G|@]|H|@]|6|$]]|$A|I|C|J|2|K|F|S|G|@]|H|@]|6|$L|M]]|$A|N|C|O|2|E|F|T|G|@]|H|@$P|U|Q|V|A|W]]|6|$]]]]

You can also use an operator

<pre class="lang-swift prettyprint-override"><code>let date = Date()
let anHourAgo = date - TimeInterval(3600.0)
</code></pre>



Apple Docs: 
<a href="https://developer.apple.com/documentation/foundation/date/2293436" rel="nofollow noreferrer">https://developer.apple.com/documentation/foundation/date/2293436</a>

entityMap|blocks|key|3pego|text|在swift+5中，您可以使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|fvb12|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!)|code-block|syntax|javascript|so7j|输出将会像咆哮|anbvr|Current+DateTime-->+2019-12-20+09:40:08
One+Hour+Previous+Date+Time-->+2019-12-20+08:40:08^0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|L|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|M|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|N|9|@]|A|@]|B|$]]|$2|J|4|K|6|E|8|O|9|@]|A|@]|B|$F|G]]]]

In swift 5 You can use

<pre><code> 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!)
</code></pre>

Out put will Be like bellow

<pre><code>Current DateTime--&gt; 2019-12-20 09:40:08
One Hour Previous Date Time--&gt; 2019-12-20 08:40:08
</code></pre>

entityMap|blocks|key|fs51q|text|这适用于iOS+13+/+Swift+5。Sourabh+Sharma|type|unstyled|depth|inlineStyleRanges|entityRanges|data|fpj7k|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"
++++}
}|code-block|syntax|javascript|87div|用法：|bndct|var+date+=+Date()+//+Or+any+date+you+wish+to+convert+to+text
print("\(date.timeAgoSinceNow())")+//+"Just+Now"^0|0|0|0^^$0|$]|1|@$2|3|4|5|6|7|8|L|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|M|9|@]|A|@]|B|$F|G]]|$2|H|4|I|6|7|8|N|9|@]|A|@]|B|$]]|$2|J|4|K|6|E|8|O|9|@]|A|@]|B|$F|G]]]]

This works for iOS 13 / Swift 5. Credit goes to <a href="https://stackoverflow.com/users/3933302/sourabh-sharma">Sourabh Sharma</a>

<pre><code>func timeAgoSinceNow(numericDates: Bool = true) -&gt; 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 &gt;= 1 {
 return year &gt;= 2 ? "\(year) years ago" : numericDates ? "1 year ago" : "Last year"
 } else if month &gt;= 1 {
 return month &gt;= 2 ? "\(month) months ago" : numericDates ? "1 month ago" : "Last month"
 } else if weekOfYear &gt;= 1 {
 return weekOfYear &gt;= 2 ? "\(weekOfYear) weeks ago" : numericDates ? "1 week ago" : "Last week"
 } else if day &gt;= 1 {
 return day &gt;= 2 ? "\(day) days ago" : numericDates ? "1 day ago" : "Yesterday"
 } else if hour &gt;= 1 {
 return hour &gt;= 2 ? "\(hour) hours ago" : numericDates ? "1 hour ago" : "An hour ago"
 } else if minute &gt;= 1 {
 return minute &gt;= 2 ? "\(minute) minutes ago" : numericDates ? "1 minute ago" : "A minute ago"
 } else {
 return second &gt;= 3 ? "\(second) seconds ago" : "Just now"
 }
}
</code></pre>

Usage:

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

entityMap|0|type|LINK|mutability|MUTABLE|data|url|https://stackoverflow.com/a/58065902/4488252|1|https://stackoverflow.com/a/40654331/4488252|2|https://stackoverflow.com/a/41800361/4488252|blocks|key|f7sm9|text|详细信息|unstyled|depth|inlineStyleRanges|entityRanges|fcdeh|Xcode+11.4+(11E146)，Swift+5.2|unordered-list-item|dpche|解决方案|42n8q|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
++++}
}|code-block|syntax|javascript|f6uv0|用法|99p1a|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)|2rsbg|更多|14ahq|获取组件(小时、月、天...)起始日期|offset|length|1b5on|按组件比较天数|citip|将日期转换为格式化字符串日期^0|0|0|0|0|0|0|0|0|J|0|0|0|7|1|0|0|E|2^^$0|$1|$2|3|4|5|6|$7|8]]|9|$2|3|4|5|6|$7|A]]|B|$2|3|4|5|6|$7|C]]]|D|@$E|F|G|H|2|I|J|1A|K|@]|L|@]|6|$]]|$E|M|G|N|2|O|J|1B|K|@]|L|@]|6|$]]|$E|P|G|Q|2|I|J|1C|K|@]|L|@]|6|$]]|$E|R|G|S|2|T|J|1D|K|@]|L|@]|6|$U|V]]|$E|W|G|X|2|I|J|1E|K|@]|L|@]|6|$]]|$E|Y|G|Z|2|T|J|1F|K|@]|L|@]|6|$U|V]]|$E|10|G|11|2|I|J|1G|K|@]|L|@]|6|$]]|$E|12|G|13|2|O|J|1H|K|@]|L|@$14|1I|15|1J|E|1K]]|6|$]]|$E|16|G|17|2|O|J|1L|K|@]|L|@$14|1M|15|1N|E|1O]]|6|$]]|$E|18|G|19|2|O|J|1P|K|@]|L|@$14|1Q|15|1R|E|1S]]|6|$]]]]

<h2>Details</h2>

<ul>
<li>Xcode 11.4 (11E146), Swift 5.2</li>
</ul>

<h2>Solution</h2>

<pre><code>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) -&gt; Date? {
 subtract(components, calendar: calendar)
 }

 func subtract(_ components: [Component], calendar: Calendar = Calendar.current) -&gt; Date? {
 components.reduce(self) { (result, component) -&gt; 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) -&gt; Date? {
 Date().subtract(component, calendar: calendar)
 }

 static func beforeNow(difference component: [Component], calendar: Calendar = Calendar.current) -&gt; Date? {
 Date().subtract(component, calendar: calendar)
 }
}

extension Date {
 static func - (date: Date, component: Date.Component) -&gt; 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
 }
}
</code></pre>

<h2>Usage</h2>

<pre><code>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)
</code></pre>

<h2>More</h2>

<ul>
<li><a href="https://stackoverflow.com/a/58065902/4488252">Get components (hours, months, days...) from date</a></li>
<li><a href="https://stackoverflow.com/a/40654331/4488252">Compare days by components</a></li>
<li><a href="https://stackoverflow.com/a/41800361/4488252">Convert date to formated string date</a></li>
</ul>

entityMap|blocks|key|9vl2e|text|let+now+=+Date()
let+nowMinusTwoAndAHalfHours+=+now+-+2.5*60*60

print(now)
print(nowMinusTwoAndAHalfHours)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript^0^^$0|$]|1|@$2|3|4|5|6|7|8|E|9|@]|A|@]|B|$C|D]]]]

<pre><code>let now = Date()
let nowMinusTwoAndAHalfHours = now - 2.5*60*60

print(now)
print(nowMinusTwoAndAHalfHours)
</code></pre>

entityMap|blocks|key|es2ra|text|Calendar.current.date(+byAdding:+.hour,+value:+-1,+to:+Date())|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript^0^^$0|$]|1|@$2|3|4|5|6|7|8|E|9|@]|A|@]|B|$C|D]]]]

<pre><code>Calendar.current.date( byAdding: .hour, value: -1, to: Date())
</code></pre>

I have been researching, but I couldnt find exact solution for my problem. I have been trying to get 1 hour ago from a date. How can I achieve this in swift?

How to get 1 hour ago from a date in iOS swift?

Swift

Xcode

 我一直在研究，但我找不到解决我的问题的确切方法。我一直在试着从一个小时前的约会中得到。我如何在swift中实现这一点？

问如何在iOS swift中从约会中获取1小时前的信息？
EN

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问如何在iOS swift中从约会中获取1小时前的信息？
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