您好，我正在尝试检查当前时间是否在某个时间范围内，比如 8:00 - 16:30。我下面的代码显示我可以获得当前时间作为字符串，但我不确定如何使用此值来检查它是否在上面指定的时间范围内。任何帮助将不胜感激!

var todaysDate:NSDate = NSDate()
var dateFormatter:NSDateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "HH:mm"
var dateInFormat:String = dateFormatter.stringFromDate(todaysDate)
println(dateInFormat) // 23:54

最佳答案

有很多方法可以做到这一点。就个人而言，如果可以避免的话，我不喜欢使用字符串。我宁愿处理日期组件。

下面的代码创建了 8:00 和 16:30 的日期，然后比较日期以查看当前日期/时间是否在该范围内。

它比其他人的代码长，但我认为值得学习如何使用日历对日期进行计算:

编辑#3:

这个答案是很久以前的了。我将在下面保留旧答案，但这是当前的解决方案:

@CodenameDuchess 的回答使用了一个系统函数，date(bySettingHour:minute:second:of:matchingPolicy:repeatedTimePolicy:direction:)

使用该函数，代码可以简化为:

import UIKit

// The function `Calendar.date(bySettingHour:minute:second)` lets you 
// create date objects for a given time in the same day of given date
// For example, 8:00 today

let calendar = Calendar.current
let now = Date()
let eight_today = calendar.date(
  bySettingHour: 8,
  minute: 0,
  second: 0,
  of: now)!

let four_thirty_today = calendar.date(
  bySettingHour: 16,
  minute: 30,
  second: 0,
  of: now)!

// In recent versions of Swift Date objectst are comparable, so you can 
// do greater than, less than, or equal to comparisons on dates without
// needing a date extension

if now >= eight_today &&
  now <= four_thirty_today
{
  print("The time is between 8:00 and 16:30")
}

为了历史的完整性，旧的(Swift 2)答案如下:

此代码使用日历对象获取当前日期的日/月/年，并添加所需的小时/分钟组件，然后为这些组件生成日期。

import UIKit
//-------------------------------------------------------------
//NSDate extensions.
extension NSDate
{
  /**
  This adds a new method dateAt to NSDate.

  It returns a new date at the specified hours and minutes of the receiver

  :param: hours: The hours value
  :param: minutes: The new minutes

  :returns: a new NSDate with the same year/month/day as the receiver, but with the specified hours/minutes values
  */
  func dateAt(#hours: Int, minutes: Int) -> NSDate
  {
    let calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!

    //get the month/day/year componentsfor today's date.

    println("Now = \(self)")

    let date_components = calendar.components(
      NSCalendarUnit.CalendarUnitYear |
        NSCalendarUnit.CalendarUnitMonth |
        NSCalendarUnit.CalendarUnitDay,
      fromDate: self)

    //Create an NSDate for 8:00 AM today.
    date_components.hour = hours
    date_components.minute = minutes
    date_components.second = 0

    let newDate = calendar.dateFromComponents(date_components)!
        return newDate
  }
}
//-------------------------------------------------------------
//Tell the system that NSDates can be compared with ==, >, >=, <, and <= operators
extension NSDate: Equatable {}
extension NSDate: Comparable {}

//-------------------------------------------------------------
//Define the global operators for the 
//Equatable and Comparable protocols for comparing NSDates

public func ==(lhs: NSDate, rhs: NSDate) -> Bool
{
  return lhs.timeIntervalSince1970 == rhs.timeIntervalSince1970
}

public func <(lhs: NSDate, rhs: NSDate) -> Bool
{
  return lhs.timeIntervalSince1970 < rhs.timeIntervalSince1970
}
public func >(lhs: NSDate, rhs: NSDate) -> Bool
{
  return lhs.timeIntervalSince1970 > rhs.timeIntervalSince1970
}
public func <=(lhs: NSDate, rhs: NSDate) -> Bool
{
  return lhs.timeIntervalSince1970 <= rhs.timeIntervalSince1970
}
public func >=(lhs: NSDate, rhs: NSDate) -> Bool
{
  return lhs.timeIntervalSince1970 >= rhs.timeIntervalSince1970
}
//-------------------------------------------------------------

let now = NSDate()
let eight_today = now.dateAt(hours: 8, minutes: 0)
let four_thirty_today = now.dateAt(hours:16, minutes: 30)

if now >= eight_today &&
  now <= four_thirty_today
{
  println("The time is between 8:00 and 16:30")
}

编辑:

这个答案中的代码已经为 Swift 3 改变了很多。

而不是使用 NSDate ，这对我们本地人来说更有意义 Date对象，和 Date对象是 Equatable和 Comparable “开箱即用”。

因此我们可以去掉 Equatable和 Comparable < 的扩展和定义, >和 =运营商。

然后我们需要对 dateAt 中的语法进行大量调整函数遵循 Swift 3 语法。新扩展在 Swift 3 中看起来像这样:

swift 3 版本:

import Foundation

extension Date
{

  func dateAt(hours: Int, minutes: Int) -> Date
  {
    let calendar = NSCalendar(calendarIdentifier: NSCalendar.Identifier.gregorian)!

    //get the month/day/year componentsfor today's date.


    var date_components = calendar.components(
      [NSCalendar.Unit.year,
       NSCalendar.Unit.month,
       NSCalendar.Unit.day],
      from: self)

    //Create an NSDate for the specified time today.
    date_components.hour = hours
    date_components.minute = minutes
    date_components.second = 0

    let newDate = calendar.date(from: date_components)!
    return newDate
  }
}


let now = Date()
let eight_today = now.dateAt(hours: 8, minutes: 0)
let four_thirty_today = now.dateAt(hours: 16, minutes: 30)

if now >= eight_today &&
  now <= four_thirty_today
{
  print("The time is between 8:00 and 16:30")
}

关于swift - 如何快速检查时间是否在特定范围内，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29652771/