I have a piece of code that basically acts in 2 parts:
Part 1: The user sets a Date with a UIDatePicker. For example, the user selects 1 day ahead from the current date. So the selected new date is 5/19/16 instead of 5/18/16.
Part 1 code
let dateFormatter = NSDateFormatter()
dateFormatter.locale = NSLocale.currentLocale()
var dateString = "May-19-2016"
dateFormatter.dateFormat = "MMMM-dd-yyyy"
var due_date = dateFormatter.dateFromString(dateString)!
Part 2: I have created code that counts how many days are left from the selected date to the current date. In this example, somehow my code is saying its 0 days before tomorrow. Here is the code for the second part:
Second Part:
func computeDates(dueDate:NSDate)-> Int {
let currentDate = NSDate()
// Adding days to currentDate
let daysToAdd = 1
// Adding on Unit to the current instance
let calculateDate = NSCalendar.currentCalendar().dateByAddingUnit(NSCalendarUnit.Day, value: daysToAdd, toDate: currentDate, options: NSCalendarOptions.init(rawValue: 0))
// Figure out many days from may 3rd
let cal = NSCalendar.currentCalendar()
let unit = NSCalendarUnit.Day
let components = cal.components(unit, fromDate: currentDate, toDate: dueDate, options: [])
let countLeft = components.day
return countLeft
}
print("Days left: \(computeDates(due_date)) ")
// Tests
let calc_date = computeDates(due_date)
if calc_date <= -1 {
print("Yesterday")
} else if calc_date == 0 {
print("Today")
} else if calc_date > 1 {
print("Tomorrow")
}
In the part 1 example, I used a static date which I use to test this code. In this part, I set May 19, 2016, one day ahead. In the second part below in the if statement, It somehow says I have 0 days left and from what i am trying to do, it's suppose to say 1 day left before tomorrow the 19th.
Another example, If i change the 19th to the 20th, I want it to say "In 2 days" from now.
Now if I revert the day to lets say, the 15th of may (in the past), Then the if statement would say something like Overdue or the past.
How can I solve this?
It would help if you thought of NSDate as a structure that operates with the number of seconds from 2001. It means if you pick a "date", it contains "date and time". All you need to do to calculate the correct number of days between specific "dates" is to truncate a time component.
But if you only need to check whether the provided date is Yesterday, Today, or Tomorrow, NSCalendar has methods for this purpose:
Objective-C:
- (BOOL)isDateInToday:(NSDate *)date NS_AVAILABLE(10_9, 8_0);
- (BOOL)isDateInYesterday:(NSDate *)date NS_AVAILABLE(10_9, 8_0);
- (BOOL)isDateInTomorrow:(NSDate *)date NS_AVAILABLE(10_9, 8_0);
And Swift:
#available(OSX 10.9, *)
public func isDateInYesterday(date: NSDate) -> Bool
#available(OSX 10.9, *)
public func isDateInTomorrow(date: NSDate) -> Bool
#available(OSX 10.9, *)
public func isDateInWeekend(date: NSDate) -> Bool
Related
I have 2 dates. I don't care about the date portion, just the time.
How can I compare 2 dates and get the timeinterval between 2 dates?
Should I set the dates to 01-01-2000 and leave the time alone to compare?
Use DateComponents and get the hour, minute, and second of the two dates. At this point you have to assume a full 24 hour, 86400 seconds per day. There's no need to worry about daylight saving or leap seconds or anything since you are doing date independent calculations.
Convert the hours, minutes, and seconds into total seconds of the day for the two dates. Then simply subtract the two totals and you have the difference.
Here's a helpful Date extension:
extension Date {
func secondsSinceMidnight() -> TimeInterval {
let comps = Calendar.current.dateComponents([.hour,.minute,.second], from: self)
return TimeInterval(comps.hour! * 3600 + comps.minute! * 60 + comps.second!)
}
func timeDifference(to date: Date) -> TimeInterval {
return date.secondsSinceMidnight() - self.secondsSinceMidnight()
}
}
Call timeDifference(to:) using your two dates and you will get the difference in seconds ignoring the date portion of the dates.
A negative result means that the to date is closer to midnight.
This is an alternative to rmaddy's solution completely based on DateComponents
extension Date {
func timeComponents() -> DateComponents {
return Calendar.current.dateComponents([.hour,.minute,.second], from: self)
}
func timeDifference(to date: Date) -> Int {
return Calendar.current.dateComponents([.second], from: date.timeComponents(), to: self.timeComponents()).second!
}
}
If you have two dates you can use the method timeIntervalSince(Date).
For instance:
func calculateElapsedTime(from someTime: Date) -> TimeInterval {
let currentTime = Date()
var elapsedTime = currentTime.timeIntervalSince(someTime)
return elapsedTime
}
If you only want to consider the time difference between the two dates, you first have to normalize the date. This can be done in the following cumbersome way:
let currentDate = Date()
let anotherDate = Date(timeInterval: 60, since: currentDate)
let formatter = DateFormatter()
formatter.timeStyle = .short
let currentTime = formatter.string(from: currentDate)
let anotherTime = formatter.string(from: anotherDate)
let currentIntervalTime = formatter.date(from: currentTime)
let anotherIntervalTime = formatter.date(from: anotherTime)
let elapsedTime = anotherIntervalTime?.timeIntervalSince(currentIntervalTime!)
I have a UIDatePicker which is available for days from today to the next week ( from Date() to Date().day + 7 ).
Suppose that today is 30th day of the month, so the available days to choose are 30th day of this month and first to 6th day of next month.
In this case, I need to change the datePicker month to next month as the user change day from 30 to 1.
But the problem is:
"When I change the day to an invalid one, the .change method give me the least valid day."
Example:
Assumptions:
Today = 28 July.
Choosable dates = 28 July to 3 August.
What I need:
User can not choose the days before 28 July and not after 3 August.
When user wants to change day to 1, 2 or 3 August, the datePicker itself change the month to August and make 1, 2 and 3 available to
be chosen by user.
Main Problem
When user change the day to 1, 2 or 3, I can not get the 1, 2 or 3! and it returns me "28"!
Just set maximumDate property of your UIDatePicker to desired date.
func setupDatePicker(){
var currDateComponents = getDateComponents(fromDate: Date())
var maxDateComponents = currDateComponents
if let date = currDateComponents?.day{
maxDateComponents?.day = date + 7
}
self.datePicker?.maximumDate = getDate(fromDateComponents: maxDateComponents)
}
func getDateComponents(fromDate date: Date?)-> DateComponents?{
let calendar = Calendar(identifier: .gregorian)
var dateComponents: DateComponents? = nil
if(date != nil){
dateComponents = calendar.dateComponents([.day, .month, .year], from: date!)
}
return dateComponents
}
func getDate(fromDateComponents dateComponents:DateComponents?)-> Date?{
let calendar = Calendar(identifier: .gregorian)
if let componentsBasedDate = calendar.date(from: dateComponents!) {
return componentsBasedDate
}
return nil
}
Call this function in viewDidLoad to setup calendar for setting maximum and minimum date:
fileprivate func setupCalendar() {
datePicker.minimumDate = Calendar.current.date(byAdding: .day, value: 0, to: ServerTime.sharedInstance.nowTime)
datePicker.maximumDate = Calendar.current.date(byAdding: .day, value: +7, to: ServerTime.sharedInstance.nowTime)
}
for calculate days between shown date and current date I've used this method:
extension Date {
//Calculate days between two day objects
func daysBetween(_ date: Date) -> Int {
let calendar = NSCalendar.current
// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDay(for: date)
let date2 = calendar.startOfDay(for: self)
let components = calendar.dateComponents([.day], from: date1, to: date2)
return components.day ?? 0 // This will return the number of day(s) between dates
}
}}
In fact, it is impossible to get date before they chose. And according to unavailability of days in next month before changing the month, I can not use UIDatePicker to handle it.
So Finally I implemented my custom UIPickerView.
as #holex said.
Thank you all for answering.
I need to update my watchOS complication at midnight every day.
startOfDay is the beginning of the day (i.e., 12 AM today).
Should I add a day to the start of today like this?
func getNextRequestedUpdateDateWithHandler(handler: (NSDate?) -> Void) {
// Call the handler with the date when you would next like to be given the opportunity to update your complication content
let startOfDay = NSDate().startOfDay
let components = NSDateComponents()
components.day = 1
let startOfNextDay = NSCalendar.currentCalendar().dateByAddingComponents(components, toDate: startOfDay, options: NSCalendarOptions())
handler(startOfNextDay)
}
Or should I not add a day to the code, and just do something like this:
func getNextRequestedUpdateDateWithHandler(handler: (NSDate?) -> Void) {
// Call the handler with the date when you would next like to be given the opportunity to update your complication content
let startOfDay = NSDate().startOfDay
handler(startOfDay)
}
You'd want to advance the date one day, since you want your next requested update to occur at tomorrow's midnight. The first method would do what you want, but you can simplify it as follows:
let calendar = NSCalendar.currentCalendar()
let startOfDay = calendar.startOfDayForDate(NSDate())
let startOfNextDay = calendar.dateByAddingUnit(.Day, value: 1, toDate: startOfDay, options: NSCalendarOptions())!
The second code would return today's 12 AM, which would already be in the past.
I'm trying to display the time of something being open based on what day it is. Something like this:
Opening Hours
**Monday: 8:00-17:00**
Tuesday: 8:00-17:00
Wednesday: 8:00-17:00
Thursday: 8:00-17:00
Friday: 8:00-17:00
Saturday: 8:00-13:00
Sunday: closed
Or simply display
Monday: 8:00-17:00
My assumption would be to use switch statements, but what would I need to do to find out what day it is?
Another solution could be:
import Foundation
let today = NSDate()
let dateFormatter = NSDateFormatter()
let currentDay = NSCalendar.currentCalendar().component(.Weekday, fromDate:today);
dateFormatter.dateFormat = "EEEE"
let dayOfWeekString = dateFormatter.stringFromDate(today)
switch currentDay
{
case 2,3,4,5:
print("\(dayOfWeekString): 8:00 - 17:00")
case 6:
print("\(dayOfWeekString): 8:00 - 13:00")
default:
print("\(dayOfWeekString): closed")
}
You can use component(_:fromDate:) to get the week day from the current date. That would look like:
let currentDay = NSCalendar.currentCalendar().component(.Weekday, fromDate:NSDate());
Based on the value you get for currentDay, you can provide the correct opening hours.
You can make use of NSCalendar to get the .Weekday unit as an integer (Sunday through Saturday as 1 ... 7 for the Gregorian calendar).
Given you know the day of the week represented as an Int, rather than using a switch statement, you could use a [Int: String] dictionary for the different opening hours.
let calendar = NSCalendar.currentCalendar()
let today = calendar.component(.Weekday, fromDate: NSDate())
// Gregorian calendar: sunday = 0, monday = 1, ...
let openingHours: [Int: String] = [1: "Sunday: closed", 2: "Monday: 8:00-17:00", 3: "Tuesday: 8:00-17:00"] // ...
print("Opening hours:\n\(openingHours[today] ?? "")")
/* Opening hours:
Monday: 8:00-17:00 */
Another alternative is to create a computed property extension to NSDate() that returns the current weekday as a String
extension NSDate {
var weekday : String {
let formatter = NSDateFormatter()
formatter.dateFormat = "EEEE"
return formatter.stringFromDate(self)
}
}
This can be readily used with a [String: String] dictionary for holding the set of weekday : opening hours:
/* example usage */
let openingHours: [String: String] =
["Sunday": "closed",
"Monday": "8:00-17:00",
"Tuesday": "8:00-17:00"] // ...
let today = NSDate().weekday
print("Opening hours:\n\(today): \(openingHours[today] ?? "")")
/* Opening hours:
Monday: 8:00-17:00 */
Rather than going with switch statements I would prefer a more generic solution. This is also a nice demonstration of leveraging tuples and type aliases for enhancing code expressiveness and readability.
typealias Time = (start: Int, end: Int)
// starting with Sunday
let openTimes: [Time] = [(0,0), (9,17), (9,17), (9,17), (9,17), (9,17), (9,12)]
let flags : NSCalendarUnit = [.Hour, .Weekday]
func isOpenAtTime(date: NSDate) -> Bool {
let time = NSCalendar.currentCalendar().components(flags, fromDate: date)
let openingHours = openTimes[time.weekday - 1]
let hour = time.hour
return hour >= openingHours.start && hour <= openingHours.end
}
You might want to handle a few edge cases as well, but you get the idea.
You could make this work with more granular time by using minutes instead of hours.
i have a date say 2 March 2016 stored as NSUserDefaults and i want to add a new row in TableView every time a new Month is about to come , so what should i do for accomplishing this , IMO comparing the stored Date and Current Date and if
in Curent Date a new Month is about to come in next 7 days then add the
row into table but i don't know where to start, anyone can give me some hint for checking current date's next 7 days for if a new months is about to come
and if my approach is not good enough then please correct me it'll be so appreciated by me and helpful for me
please see example for better understanding :
storedDate = 2 March 2016
currentDate = 26 March 2016
if CurrentDate + 1 Week == newMonth {
//add the Row into TableView
}
You can add an Extension to NSDate and then do all sorts of day/month addition
This method you can use to add 7 days to the current date...
func dateByAddingDays(daysToAdd: Int)-> NSDate {
let dateComponents = NSDateComponents()
dateComponents.day = daysToAdd
let newDate = NSCalendar.currentCalendar().dateByAddingComponents(dateComponents, toDate: self, options: .MatchFirst)
return newDate!
}
This method to add months to current date
func dateByAddingMonths(monthsToAdd: Int)-> NSDate {
let dateComponents = NSDateComponents()
dateComponents.month = monthsToAdd
let newDate = NSCalendar.currentCalendar().dateByAddingComponents(dateComponents, toDate: self, options: .MatchFirst)
return newDate!
}
Then you need to check that date you created and see if it its a different month than the one that is stored..
func compareMonths(newDate:NSDate)-> Bool {
let today = NSDate()
let todayPlusSeven = today.dateByAddingDays(7)
return todayPlusSeven.isNextMonth(storedDate)
}
Using this method to check if the months of 2 dates are the same
func isNextMonth(storedDate: NSDate)-> Bool {
return isSameMonthAsDate(storedDate.dateByAddingMonth(1))
}
func isSameMonthAsDate(compareDate: NSDate)-> Bool {
let comp1 = NSCalendar.currentCalendar().components([NSCalendarUnit.Year, NSCalendarUnit.Month], fromDate: self)
let comp2 = NSCalendar.currentCalendar().components([NSCalendarUnit.Year, NSCalendarUnit.Month], fromDate: compareDate)
return ((comp1.month == comp2.month) && (comp1.year == comp2.year))
}
An oldie but still goodie, is this page of Date helpers from Erica Sadun's github page here They are all in Obj-c but can be converted to swift easily enough. I still reference it when i need help doing date math