Question:
I need to compare 2 times - the current time and a set one. If the set time is in the future, find out how many minutes remain until said future time.
Other Info:
I am currently using
let date = NSDate()
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.CalendarUnitHour | .CalendarUnitMinute, fromDate: date)
let hour = components.hour
let minutes = components.minute
which I stole from another answer on SO about how to get the current time in Int format. I then split the future time into hour (Int) and minutes(Int) and compare those... But that gets odd when you go over the hour barrier.
You have compare function to compare 2 NSDate to know which one is more recent. It returns NSCompareResults
enum NSComparisonResult : Int {
case OrderedAscending
case OrderedSame
case OrderedDescending
}
Get distance (in seconds) from 2 NSDate, you have .timeIntervalSinceDate(). Then, you know how to convert to minutes, hours, ...
let date1 : NSDate = ...
let date2 : NSDate = ...
let compareResult = date1.compare(date2)
let interval = date1.timeIntervalSinceDate(date2)
just to add to #tyt_g207's answer, I found the compare method, but hadn't found NSComparisonResult.OrderedDescending and the others. I used something like the modified below to check an expiration date against today's date
let date1 : NSDate = expirationDate
let date2 : NSDate = NSDate() //initialized by default with the current date
let compareResult = date1.compare(date2)
if compareResult == NSComparisonResult.OrderedDescending {
println("\(date1) is later than \(date2)")
}
let interval = date1.timeIntervalSinceDate(date2)
let dateComparisionResult: NSComparisonResult = currentDate.compare("Your Date")
if dateComparisionResult == NSComparisonResult.OrderedAscending
{
// Current date is smaller than end date.
}
else if dateComparisionResult == NSComparisonResult.OrderedDescending
{
// Current date is greater than end date.
}
else if dateComparisionResult == NSComparisonResult.OrderedSame
{
// Current date and end date are same.
}
Use timeIntervalSinceDate of date on further date and pass the earlier date as parameter, this would give the time difference
Related
I have a date in string format, example:- "2017-07-31" or can be multiple dates (any) in string format. My requirement is to check this date to current date and if it is greater than 0 and less than 15, then that time I have to do another operation.
So first I am converting that date string to in date format. But it is giving one day ago date. Here is my code:
//Date from string
func dateFromString(date : String) -> Date {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let currentDate = (dateFormatter.date(from: date))//(from: date))
return currentDate!
}
Ex. my date is "2017-08-30" and this function is returning 2017-08-29 18:30:00 +0000 in date format. It means 1 day ago. I am little bit confuse about dates operation. I read so many blogs also.
After that I have to check this date to current date if it is in between 0 < 15 than I will do other operation.
Comparing two dates:
extension Date {
func daysBetweenDate(toDate: Date) -> Int {
let components = Calendar.current.dateComponents([.day], from: self, to: toDate)
return components.day ?? 0
}
}
If my date is today date and comparing to tomorrow date then also it is giving 0 days difference. Why?
If – for example – the current date is 2017-07-31 at 11AM then the
difference to 2017-08-01 (midnight) is 0 days and 13 hours, and that's
why you get "0 days difference" as result.
What you probably want is to compare the difference between the start
of the current day and the other date in days:
extension Date {
func daysBetween(toDate: Date) -> Int {
let cal = Calendar.current
let startOfToday = cal.startOfDay(for: self)
let startOfOtherDay = cal.startOfDay(for: toDate)
return cal.dateComponents([.day], from: startOfToday, to: startOfOtherDay).day!
}
}
Try this method for convert string to date:
func dateFromString(date : String) -> Date {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
dateFormatter.timeZone = TimeZone.init(abbreviation: "UTC")
let currentDate = (dateFormatter.date(from: date))//(from: date))
return currentDate!
}
Try this to compare the time between two dates in seconds :
var seconds = Calendar.current.dateComponents([.second], from: date1!, to: date2!).second ?? 0
seconds = abs(seconds)
let min = seconds/60 // this gives you the number of minutes between two dates
let hours = seconds/3600 // this gives you the number of hours between two dates
let days = seconds/3600*24 // this gives you the number of days between two dates
I'm making a kind of challenge based app that requires that the user comes back every day. If he misses one day, he has to start all over again.
My problem is my dateChanged()-function; the first thing is, that it doesn't work very reliable, the second is that I just check if the date changed, I accordingly don't know if there were one or two days between using the app.
Here's my current function:
public func changeDays()
{
myFormatter.dateStyle = .short
myFormatter.locale = Locale(identifier: "de_DE")
oldDate = defaults.string(forKey: "oldDate")!
let newDate = Date()
let newDateString = myFormatter.string(from: newDate)
if newDateString == oldDate
{
NumberOfDaysInARow.text = "\(days) / 30"
}
else if newDateString != oldDate
{
days += 1
NumberOfDaysInARow.text = "\(days) / 30"
defaults.set(days, forKey: "days")
}
oldDate = newDateString
defaults.set(oldDate, forKey: "oldDate")
}
Just today it started giving me a fatal error when starting the app on my iPhone, did not happen in the simulator though... weird.
How do I have to change my function to make it a 100% reliable (and working) while also being able to check the amount of time between the two dates?
Thank you for having a look! Have a great day
You could extend Date with the function below that returns the amount of days from another date.
extension Date {
// Returns the amount of days from another date
func days(from date: Date) -> Int {
return Calendar.current.dateComponents([.day], from: date, to: self).day ?? 0
}
}
Instead of saving oldDate as a string you can set it to defaults as a date:
defaults.set(Date(), forKey: "oldDate")
You can get the old date from defaults using:
let oldDate = defaults.object(forKey:"oldDate") as! Date
Once you have your old date
let dateNow = Date()
let timeDifference = dateNow.days(from: oldDate!)
If timeDifference > 1 {
// older than 1 day
} else {
// Streak still alive
}
}
If you look in the documentation you will see that Date has a method whose sole purpose is too determine the interval between two dates timeIntervalSince(_:).
If you set the old date to always be 11:59PM on the day it was last used you only have to see if the interval is greater than 24 hours worth of seconds (60 seconds * 60 minutes * 24 hours).
You may want to look at the docs for DateComponents for help creating a date that uses the current date but with a specific time.
I have a dictionary like this:
var dic = [NSDate: Int]()
it is used in my iOS to-do app to get the number of finished tasks of a particular date. I only care about the year, month and day sections in NSDate and also want to be able to get the number of tasks in a particular date using this dictionary, how can I do that? thanks.
Instead of storing your date as NSDate in your dictionary you can save it as String so that comparison will be easier. Use following code to store it as a string
func dateFromString(date : NSDate) -> String {
var dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
return dateFormatter.stringFromDate(date)
}
You can pass NSDate() to above function and it will give you string containing only year, month and date. For retrieving your data from dictionary use following.
func dateFrom(year:Int, month:Int, day:Int) -> String {
let components = NSDateComponents()
components.year = year
components.month = month
components.day = day
let gregorian = NSCalendar(identifier:NSCalendarIdentifierGregorian)
let date = gregorian!.dateFromComponents(components)
return dateFromString(date!)
}
You can pass year, month and date to above function and it will return corresponding date in string format. So your dictionary operations will look like
dict[dateFromString(NSDate())] = 1 //for insertion or updation
let numOfTasks = dict[dateFrom(2016, month: 1, day: 15)] //to get task for any particular day
EDIT
If you want to proceed with NSDate as key for your dictionary then you'll have to modify above code as follows. dateFrom will return date with year,month and date of your choice, and time will be some constant value. Time will be set to midnight in your current time zone if you don't set it.
func dateFrom(year:Int, month:Int, day:Int) -> NSDate {
let components = NSDateComponents()
components.year = year
components.month = month
components.day = day
let gregorian = NSCalendar(identifier:NSCalendarIdentifierGregorian)
let date = gregorian!.dateFromComponents(components)
return date!
}
And for getting current date use following so that you store date object with current year, date, month and time to some constant value.
func getCurrentDate()->NSDate {
let date = NSDate()
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Day , .Month , .Year], fromDate: date)
return dateFrom(components.year, month: components.month, day: components.day)
}
Usage will be as follows
dict[getCurrentDate()] = i //for insertion or updation
let numOfTasks = dict[dateFrom(2016, month: 1, day: 15)] //to get task for any particular day
I am making a TimeTable app, and i have a method that adds 1 week to the current date, this works as it is supposed to, however if the week transitions from December to January, it adds 1 day extra.
Here is my code:
func getWeekDates(var date: NSDate) -> [NSDate] {
var dates: [NSDate] = [NSDate]()
for var i = 0; i < 5; i++ {
date = date.dateAtWeekStart() + 1.day - 1.week
date += i.day
dates.append(date)
}
return dates
}
And dateAtWeekStart():
func dateAtWeekStart() -> NSDate {
let flags : NSCalendarUnit = [NSCalendarUnit.Year,NSCalendarUnit.Month ,
NSCalendarUnit.WeekOfYear,
NSCalendarUnit.Weekday]
let components = NSCalendar.currentCalendar().components(flags, fromDate: self)
components.weekday = 1 // Sunday
components.hour = self.hour
components.minute = self.minute
components.second = self.second
return NSCalendar.currentCalendar().dateFromComponents(components)!
}
(dateAtWeekStart() is a function made in an extension to NSDate)
The reason i am adding 1 day and removing 1 week, is because dateAtWeekStart returns next sunday, so for example 08-10-2015.dateAtWeekStart() returns 11-10-2015.
So this works fine normally, however if we take this year as an example, 29-12-2015.dateAtWeekStart() returns 04-01-2015 instead of 03-01-2016.
By the way, the region on the device is set to Denmark.
dateAtWeekStart, comes from a helper class called SwiftDate made by malcommac: https://github.com/malcommac/SwiftDate
UPDATE EDIT:
I am still having trouble figuring out how to fix this, i tried adding year to components like so: components.year = self.year, but it sets the year to 2014 for some reason when returning the components..
That dateAtWeekStart() method simply does not work.
[.YearForWeekOfYear, .WeekOfYear] are sufficient as calendar units to
determine the (start of a) week uniquely. The additional units can make
the calculation undetermined. Also you can not just set
components.weekday = 1 because in some regions Monday (2) is the first
day of the week.
So it is actually a bit easier:
extension NSDate {
func dateAtWeekStart() -> NSDate {
let cal = NSCalendar.currentCalendar()
// cal.firstWeekday = 1 // If you insist on Sunday being the first day of the week.
let flags : NSCalendarUnit = [.YearForWeekOfYear, .WeekOfYear]
let components = cal.components(flags, fromDate: self)
return cal.dateFromComponents(components)!
}
}
This should work in all cases and give the start of the week (at midnight) for the given date. There are also other methods
one could use, such as rangeOfUnit().
If you want Sunday to be considered as the first day of the week
instead of using the user's regional settings
then you have to set the firstWeekday property of the calendar.
The code to add days or weeks to a date also looks highly suspicious.
The extensions method for Int in the SwiftDate project treats
a day as 24*60*60 seconds. This is not correct, because in regions with
daylight saving times, a day can have 23 or 25 hours when the clocks
are adjusted. The correct way to add one week to a date is to
use calendar components again:
date = cal.dateByAddingUnit(.WeekOfYear, value: 1, toDate: date, options: [])!
Update for Swift 3:
extension Date {
func dateAtWeekStart() -> Date {
var cal = Calendar.current
// cal.firstWeekday = 1 // If you insist on Sunday being the first day of the week.
let components = cal.dateComponents([.yearForWeekOfYear, .weekOfYear], from: self)
return cal.date(from: components)!
}
}
Hello I have a method that returns an array of times for each day.
prayTimesDate(date: NSDate, latitide : Double, longitude : Double, timeZone : Double) -> NSMutableArray
I need to iterate through a whole year or maybe a date range to get an array of times for each day in a whole year. I found alot of references in ruby and python on how to do this but I couldn't find anything for swift or objective-c. Is there any built in methods in swift that will accomplish this? If not can someone help me out as I am still new in programming. Any input is greatly appreciated.
This is the objective-c code for the method I'm linking to my swift project
- (NSMutableArray *)prayerTimesDate:(NSDate *)date latitude:(double)latitude longitude:(double)longitude andTimezone:(double)timezone
{
unsigned unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:unitFlags fromDate:date];
NSInteger year = [components year];
NSInteger month = [components month];
NSInteger day = [components day];
return [self getDatePrayerTimesForYear:year month:month day:day latitude:latitude longitude:longitude andtimeZone:timezone];
}
Assuming your prayerTimesDate: method is already returning the expected result, you can loop through each day of the year while repeatedly call prayerTimesDate: to get an array containing the prayer times for each day, ex:
func yearlyPrayerDatesFromCurrentDate (latitude:Double, longitude:Double, timezone:Double) -> NSMutableArray {
// Set "date" to equal the current day
var date:NSDate! = NSDate()
// Increment "date" by one year to calculate the ending
// date for the loop
let gregorian:NSCalendar! = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)
let dateComponents = NSDateComponents()
dateComponents.year = 1
let endingDate:NSDate! = gregorian.dateByAddingComponents(dateComponents, toDate: date, options: nil)
// Create an array to hold *all* the returned
// results for the year
var datesArray = NSMutableArray()
// Loop through each date until the ending date is
// reached
while date.compare(endingDate) != NSComparisonResult.OrderedDescending {
// Call your prayerTimesDate: method on the current
// date to get that date's prayer times and add the
// times from the returned array to the datesArray
datesArray.addObjectsFromArray(prayerTimesDate(date, latitude: latitude, longitude: longitude, andTimezone: timezone))
// increment the date by 1 day
let dateComponents = NSDateComponents()
dateComponents.day = 1
date = gregorian.dateByAddingComponents(dateComponents, toDate: date, options: nil)
}
return datesArray
}
Here is another example for a period over 14 days (without NSCalendar):
let ti:NSTimeInterval = 24*60*60 //one day
let dateFrom = NSDate() //Now
let dateTo = dateFrom.dateByAddingTimeInterval(24*60*60*14) //14 Days later
var nextDate = NSDate()
var endDate = dateTo.dateByAddingTimeInterval(ti)
while nextDate.compare(endDate) == NSComparisonResult.OrderedAscending
{
print("nextDate:", nextDate)
nextDate = nextDate.dateByAddingTimeInterval(ti)
}
Create an NSDateComponents instance for 1 day and NSDate objects for each time on the first day. Now you can iterate over the number of days you want (or until you hit then end date) and then you can use dateByAddingComponents:toDate:options: of the calendar to get the new date for each day.
From Apple doc: To compute a sequence of dates, use the enumerateDatesStartingAfterDate:matchingComponents:options:usingBlock: method instead of calling this method ( - nextDateAfterDate:matchingComponents:options: ) in a loop with the previous loop iteration's result.
As I got, it will iterate all dates that matched with "matchingComponents" till you finish iteration with "stop.memory = true"
//: Playground - noun: a place where people can play
import UIKit
let calendar = NSCalendar.currentCalendar()
let startDate = calendar.startOfDayForDate(NSDate())
let finishDate = calendar.dateByAddingUnit(.Day, value: 10, toDate: startDate, options: [])
let dayComponent = NSDateComponents()
dayComponent.hour = 1
calendar.enumerateDatesStartingAfterDate(startDate, matchingComponents: dayComponent, options: [.MatchStrictly]) { (date, exactMatch, stop) in
print(date)
if date!.compare(finishDate!) == NSComparisonResult.OrderedDescending {
// .memory gets at the value of an UnsafeMutablePointer
stop.memory = true
}
}