import UIKit
var timeInterval = DateComponents(
month: 2,
day: 3,
hour: 4,
minute: 5,
second: 6
)
let futureDate = Calendar.current.date(byAdding: timeInterval, to: Date())!
print("2 months, 3 days, 4 hours, 5 minutes, and 6 seconds from now is \(futureDate.description(with: Locale(identifier: "en_US"))).")
// Overloading + and - so that we can add and subtract DateComponents
// ==================================================================
func +(_ lhs: DateComponents, _ rhs: DateComponents) -> DateComponents {
return combineComponents(lhs, rhs)
}
func -(_ lhs: DateComponents, _ rhs: DateComponents) -> DateComponents {
return combineComponents(lhs, rhs, multiplier: -1)
}
func combineComponents(_ lhs: DateComponents,
_ rhs: DateComponents,
multiplier: Int = 1)
-> DateComponents {
var result = DateComponents()
result.nanosecond = (lhs.nanosecond ?? 0) + (rhs.nanosecond ?? 0) * multiplier
result.second = (lhs.second ?? 0) + (rhs.second ?? 0) * multiplier
result.minute = (lhs.minute ?? 0) + (rhs.minute ?? 0) * multiplier
result.hour = (lhs.hour ?? 0) + (rhs.hour ?? 0) * multiplier
result.day = (lhs.day ?? 0) + (rhs.day ?? 0) * multiplier
result.weekOfYear = (lhs.weekOfYear ?? 0) + (rhs.weekOfYear ?? 0) * multiplier
result.month = (lhs.month ?? 0) + (rhs.month ?? 0) * multiplier
result.year = (lhs.year ?? 0) + (rhs.year ?? 0) * multiplier
return result
}
// Let's define a couple of durations of time
// ------------------------------------------
var oneDayFiveHoursTenMinutes = DateComponents(
day: 1,
hour: 5,
minute: 10
)
var threeDaysTenHoursThirtyMinutes = DateComponents(
day: 3,
hour: 10,
minute: 30
)
// Now let's add and subtract them
// -------------------------------
let additionResult = oneDayFiveHoursTenMinutes + threeDaysTenHoursThirtyMinutes
print("1 day, 5 hours, and 10 minutes + 3 days, 10 hours, and 30 minutes equals:")
print("\(additionResult.day!) days, \(additionResult.hour!) hours, and \(additionResult.minute!) minutes.")
let subtractionResult = threeDaysTenHoursThirtyMinutes - oneDayFiveHoursTenMinutes
print("1 day, 5 hours, and 10 minutes - 3 days, 10 hours, and 30 minutes equals:")
print("\(subtractionResult.day!) days, \(subtractionResult.hour!) hours, and \(subtractionResult.minute!) minutes.")
// Overloading - so that we can negate DateComponents
// --------------------------------------------------
// We'll need to overload unary - so we can negate components
prefix func -(components: DateComponents) -> DateComponents {
var result = DateComponents()
if components.nanosecond != nil { result.nanosecond = -components.nanosecond! }
if components.second != nil { result.second = -components.second! }
if components.minute != nil { result.minute = -components.minute! }
if components.hour != nil { result.hour = -components.hour! }
if components.day != nil { result.day = -components.day! }
if components.weekOfYear != nil { result.weekOfYear = -components.weekOfYear! }
if components.month != nil { result.month = -components.month! }
if components.year != nil { result.year = -components.year! }
return result
}
let negativeTime = -oneDayFiveHoursTenMinutes
print("Negating 1 day, 5 hours, and 10 minutes turns it into:")
print("\(negativeTime.day!) days, \(negativeTime.hour!) hours, and \(negativeTime.minute!) minutes.")
// Overloading + and - so that we can add Dates and DateComponents
// and subtract DateComponents from Dates
// Date + DateComponents
func +(_ lhs: Date, _ rhs: DateComponents) -> Date
{
return Calendar.current.date(byAdding: rhs, to: lhs)!
}
// DateComponents + Dates
func +(_ lhs: DateComponents, _ rhs: Date) -> Date
{
return rhs + lhs
}
// Date - DateComponents
func -(_ lhs: Date, _ rhs: DateComponents) -> Date
{
return lhs + (-rhs)
}
// What time will it be 1 day, 5 hours, and 10 minutes from now?
// -------------------------------------------------------------
// Here's the standard way of finding out:
let futureDate0 = Calendar.current.date(
byAdding: oneDayFiveHoursTenMinutes,
to: Date()
)
// With our overloads and function definitions, we can now do it this way:
let futureDate1 = Date() + oneDayFiveHoursTenMinutes
print("Date() + oneDayFiveHoursTenMinutes = \(futureDate1.description(with: Locale(identifier: "en_US")))")
// This will work as well:
let futureDate2 = oneDayFiveHoursTenMinutes + Date()
print("oneDayFiveHoursTenMinutes + Date() = \(futureDate2.description(with: Locale(identifier: "en_US")))")
// What time was it 3 days, 10 hours, and 30 minutes ago?
// ------------------------------------------------------
// Doing it the standard way takes some work
var minus3Days5Hours30minutes = threeDaysTenHoursThirtyMinutes
minus3Days5Hours30minutes.day = -threeDaysTenHoursThirtyMinutes.day!
minus3Days5Hours30minutes.hour = -threeDaysTenHoursThirtyMinutes.hour!
minus3Days5Hours30minutes.minute = -threeDaysTenHoursThirtyMinutes.minute!
let pastDate0 = Calendar.current.date(byAdding: minus3Days5Hours30minutes, to: Date())
// With our overloads and function definitions, it's so much easier:
let pastDate1 = Date() - threeDaysTenHoursThirtyMinutes
print("Date() - threeDaysTenHoursThirtyMinutes = \(pastDate1.description(with: Locale(identifier: "en_US")))")
// Extending Date so that creating dates and debugging are simpler
// ===============================================================
extension Date {
init(year: Int,
month: Int,
day: Int,
hour: Int = 0,
minute: Int = 0,
second: Int = 0,
timeZone: TimeZone = TimeZone(abbreviation: "UTC")!) {
var components = DateComponents()
components.year = year
components.month = month
components.day = day
components.hour = hour
components.minute = minute
components.second = second
components.timeZone = timeZone
self = Calendar.current.date(from: components)!
}
init(dateString: String) {
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss zz"
self = formatter.date(from: dateString)!
}
var desc: String {
get {
let PREFERRED_LOCALE = "en_US" // Use whatever locale you prefer!
return self.description(with: Locale(identifier: PREFERRED_LOCALE))
}
}
}
// The Stevenote where the original iPhone was announced took place
// on January 9, 2007 at 10:00 a.m. PST
let iPhoneStevenoteDate = Date(year: 2007,
month: 1,
day: 9,
hour: 10,
minute: 0,
second: 0,
timeZone: TimeZone(abbreviation: "PST")!)
print("iPhoneStevenoteDate: \(iPhoneStevenoteDate.desc)")
// The original iPhone went on sale on June 27, 2007
let iPhoneReleaseDate = Date(year: 2007, month: 6, day: 27) // June 27, 2007, 00:00:00 UTC
print("iPhoneReleaseDate: \(iPhoneReleaseDate.desc)")
// The Stevenote where the original iPad was announced took place
// on January 27, 2010 at 10:00 a.m. PST
let iPadStevenoteDate = Date(dateString: "2010-01-27 10:00:00 PST")
print("iPadStevenoteDate: \(iPadStevenoteDate.desc)")
// Overloading - so that we can use it to find the difference
// between two Dates
// ==========================================================
func -(_ lhs: Date, _ rhs: Date) -> DateComponents
{
return Calendar.current.dateComponents(
[.year, .month, .weekOfYear, .day, .hour, .minute, .second, .nanosecond],
from: rhs,
to: lhs)
}
// How long was it between the announcement of the original iPhone
// and its release in the stores?
let iPhoneWait = iPhoneReleaseDate - iPhoneStevenoteDate
print("The first iPhone users had to wait this long: ")
print("\(iPhoneWait.year!) years, " +
"\(iPhoneWait.month!) months, " +
"\(iPhoneWait.weekOfYear!) weeks, " +
"\(iPhoneWait.day!) days, " +
"\(iPhoneWait.hour!) hours, and " +
"\(iPhoneWait.minute!) minutes.")
// How long ago was the first moon landing, which took place
// on July 20, 1969, 20:18 UTC?
let timeSinceMoonLanding = Date() - Date(dateString: "1969-07-20 20:18:00 UTC")
print("It’s been this long since the first moon landing: ")
print("\(timeSinceMoonLanding.year!) years, " +
"\(timeSinceMoonLanding.month!) months, " +
"\(timeSinceMoonLanding.weekOfYear!) weeks, " +
"\(timeSinceMoonLanding.day!) days, " +
"\(timeSinceMoonLanding.hour!) hours, and " +
"\(timeSinceMoonLanding.minute!) minutes.")
// Extending Int to add some syntactic magic to date components
// ============================================================
extension Int {
var second: DateComponents {
var components = DateComponents()
components.second = self;
return components
}
var seconds: DateComponents {
return self.second
}
var minute: DateComponents {
var components = DateComponents()
components.minute = self;
return components
}
var minutes: DateComponents {
return self.minute
}
var hour: DateComponents {
var components = DateComponents()
components.hour = self;
return components
}
var hours: DateComponents {
return self.hour
}
var day: DateComponents {
var components = DateComponents()
components.day = self;
return components
}
var days: DateComponents {
return self.day
}
var week: DateComponents {
var components = DateComponents()
components.weekOfYear = self;
return components
}
var weeks: DateComponents {
return self.week
}
var month: DateComponents {
var components = DateComponents()
components.month = self;
return components
}
var months: DateComponents {
return self.month
}
var year: DateComponents {
var components = DateComponents()
components.year = self;
return components
}
var years: DateComponents {
return self.year
}
}
// A quick test of some future dates
print("One hour from now is: \((Date() + 1.hour).desc)")
print("One day from now is: \((Date() + 1.day).desc)")
print("One week from now is: \((Date() + 1.week).desc)")
print("One month from now is: \((Date() + 1.month).desc)")
print("One year from now is: \((Date() + 1.year).desc)")
// What was the date 10 years, 9 months, 8 days, 7 hours, and 6 minutes ago?
let aLittleWhileBack = Date() - 10.years - 9.months - 8.days - 7.hours - 6.minutes
print("10 years, 9 months, 8 days, 7 hours, and 6 minutes ago, it was: \(aLittleWhileBack.desc)")
// Extending DateComponents to add even more syntactic magic: fromNow and ago
// ==========================================================================
extension DateComponents {
var fromNow: Date {
return Calendar.current.date(byAdding: self,
to: Date())!
}
var ago: Date {
return Calendar.current.date(byAdding: -self,
to: Date())!
}
}
// We’re now in Serious Syntax Magic Land!
// ---------------------------------------
print("2.weeks.fromNow: \(2.weeks.fromNow.desc)")
print("3.months.fromNow: \(3.months.fromNow.desc)")
let futureDate3 = (2.months + 3.days + 4.hours + 5.minutes + 6.seconds).fromNow
print("futureDate3: \(futureDate3.desc)")
let pastDate2 = (2.months + 3.days + 4.hours + 5.minutes + 6.seconds).ago
print("pastDate2: \(pastDate2.desc)")
In this article, we’ll expand on material covered in the three previous articles in this series on working with dates and times in Swift 5:
