Difference between two dateTimes in seconds vary due to different time zones - Swift 3 - swift

I need to find difference between current time (in seconds) and future start time (fetched from my web service in seconds).
I have coded the following :
let currentTime = Int64(Date().timeIntervalSince1970)
var time = Int64(timeArr[indexPath.row])
print("\(currentTime) vs \(time)")
time = time - currentTime
print("difference in time : \(time)")
let seconds = time % 60
let minutes = (time / 60) % 60
let hours = (time / 3600)
My console shows me this output:
1480400929 vs 1480552620
difference in time : 151691
The problem is that my current time is Tue Nov 29 2016 11:58:49 and the start time is 2016-11-30 17:37:00 so the difference in hours should come to around 30 hours whereas it takes the times in different time zones due to which it comes to around 42 hours. How do I fix this? I have gone through many questions for the same but nothing works. Any help would be appreciated.

If you want the difference between two date in Hours, Minutes and seconds you can use DateComponent like this.
let component = Calendar.current.dateComponents([.hour, .minute, .second], from: Date(), to: startDate)
let hours = component.hour ?? 0
let minutes = component.minute ?? 0
let seconds = component.second ?? 0
Edit: To get date from miliseconds use Date(timeIntervalSince1970:) like this.
let startDate = Date(timeIntervalSince1970: miliSeconds / 1000)
Also you can convert string to Date using DateFormatter like this.
let stringDate = "2016-11-30 17:37:00"
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
dateFormatter.timeZone = TimeZone(abbreviation: "GMT")
if let startDate = dateFormatter.date(from: stringDate) {
print(startDate)
}

Related

Swift get the remaining seconds of time on target string date

The current date time today was May 9, 2020 10:03 PM, and I have a target string date with the value of 2020-05-09 22:07:30 with the format of yyyy-MM-dd HH:mm:ss.
How can I get the remaining date from that 2 date and print the value with the string of 04:30 as the range of those 2 dates are 4 minutes and 30 seconds
What I can only do is convert the milliseconds to time format like
func msToTime(ms: Int) {
let seconds = ms % 60
let minutes = ms / 60000
return String(format: "%0.2d:%0.2d",minutes,seconds)
}
Output 04:30
But I don't know how to get the range of milliseconds from today's date time to target's date time.
Or if there's any other easier way to do it?
You can use Calendar and DateComponents to easily calculate differences between dates in whatever units you desire. For example, this gets the difference in minutes and seconds:
let dateformatter = DateFormatter()
dateformatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
let date = dateformatter.date(from: "2020-05-09 22:07:30")!
let now = Date()
let components = Calendar.current.dateComponents([.minute, .second], from: now, to: date)
print("difference: \(components.minute!):\(components.second!)")
A straightforward way, with no calculation of any kind needed:
let d1 = Date()
let s = "2020-05-09 22:07:30"
let f = DateFormatter()
f.dateFormat = "yyyy-MM-dd HH:mm:ss"
f.timeZone = TimeZone.current // or whatever
if let d2 = f.date(from: s) {
let f = DateComponentsFormatter()
f.unitsStyle = .positional
let result = f.string(from: d1, to: d2)
}
If you don't like the resulting string format of result, you can eliminate pieces of it. — However, note that this works only because no full days are involved. It isn't clear what the range of possible inputs might be or what the desired output would be if the second date were three months into the future, for example.

Convert hours form 12 hour time to 24 hour time Swift and save as an integer

I want to convert my variable for hours which is an integer into a 24 hour time system (for example, if it is 01:05:13 PM, hours will be saved as 13, minutes will be saved as 5, and seconds will be saved as 13) so that I can use it for some math later in my code to fid some differences on a scheduling app I am working on. This is my first app and I couldn't find an answer to this anywhere else so thanks for your help! Another way this code could work is getting the amount in seconds since the day has begun, if anyone knows how to do that, it would be greatly appreciated!
This is my function for getting the time and saving it as three different integers for hours, seconds, and minutes:
#IBAction func setTime() {
var date = NSDate()
//pickTimes()
var calendar = NSCalendar.current
calendar.timeZone = TimeZone(identifier: "UTC")!
var currentHour = calendar.component(.hour, from: date as Date) + 5
let currentMinutes = calendar.component(.minute, from: date as Date)
let currentSeconds = calendar.component(.second, from: date as Date)
timeText.text = ("\(currentHour):\(currentMinutes):\(currentSeconds)")
}
calendar.component(.hour, from: someDate) already gives you the time of day in 24 hour time so there's nothing else to do to solve your question.
Not sure why you are adding 5 to the hour. You set the timezone to UTC so the date will be treated as the UTC timezone. Then you add 5 to that result. That's kind of strange. If you just want the current hour in the user's locale timezone, don't change the calendar's timezone and don't add 5 to the hour.
Don't use NSDate or NSCalendar. This is Swift. Use Date and Calendar.
Updated code:
#IBAction func setTime() {
var date = Date()
//pickTimes()
var calendar = Calendar.current
var currentHour = calendar.component(.hour, from: date)
let currentMinutes = calendar.component(.minute, from: date)
let currentSeconds = calendar.component(.second, from: date)
timeText.text = ("\(currentHour):\(currentMinutes):\(currentSeconds)")
}
But it would be simpler to use a DateFormatter and set the timeStyle to .medium or maybe .long and format Date() into a string. This will give a properly localized time string.

Test whether current time of day is between two TimeIntervals

I have 2 TimeIntervals, which just represent date-agnostic times of day (e.g. 8:00 AM and 5:00 PM). So 0 represents exactly midnight, in this case, and 29,040 represents 8:04 AM. I want to check if the phone's time of day is between the two TimeIntervals.
I found a few similar Stack Overflow questions, but none of them really dealt with TimeIntervals. It seems like just using start <= Date().timeIntervalSinceReferenceDate <= end or something wouldn't work, because it would return a huge value.
What's the best way to handle this type of situation in Swift 3?
Edit: To clarify, I don't need to worry about things like daylight savings. As an example, assume that the user only wants certain things in the app to happen between the hours of X and Y, where X and Y are given to me as TimeInterval values since midnight. So it should be sufficient to check if the phone's TimeInterval since midnight on a typical day is between X and Y before completing the action.
Date().timeIntervalSinceReferenceDate returns the number of seconds since Jan 1, 2000 so no doubt it's a huge number.
It's inadvisable to store time as seconds since midnight due to this naggy little thing called Daylight Saving Time. Every year, different countries do it on different days and on different hours. For example, even though Britain and France change their clock on the same day (March 26, 2017), one makes the shift from 1AM to 2AM, the other goes from 2AM to 3AM. That's very easy to make for a mess!
Use DateComponents instead:
let calendar = Calendar.current
let startTimeComponent = DateComponents(calendar: calendar, hour: 8)
let endTimeComponent = DateComponents(calendar: calendar, hour: 17, minute: 30)
let now = Date()
let startOfToday = calendar.startOfDay(for: now)
let startTime = calendar.date(byAdding: startTimeComponent, to: startOfToday)!
let endTime = calendar.date(byAdding: endTimeComponent, to: startOfToday)!
if startTime <= now && now <= endTime {
print("between 8 AM and 5:30 PM")
} else {
print("not between 8 AM and 5:30 PM")
}
I ended up using DateComponents to calculate a TimeInterval.
let components = Calendar.current.dateComponents(
[.hour, .minute, .second], from: Date())
guard let seconds = components.second,
let minutes = components.minute,
let hours = components.hour else
{
return false
}
let currentTime = Double(seconds + minutes * 60 + hours * 60 * 60)
return startTime <= currentTime && currentTime <= endTime

Finding the time between now and at specific time using swift 3

I am trying to find the time (in seconds) between now and a specific time during that day e.g 9:00 AM and if the time now is past this specified time in the day, I would want the time between now and that set time in the next day.
My ultimate goal is to run a function at every hour from 8:00 AM to 5:00 PM, while the application is not open/ in background. If there is a better way to do this without using a timer with an interval of 24 hours then I would really appreciate some suggestions.
For adding an hour to the current time. Use the below extension
extension Date {
func addHours(_ hours: Int) -> Date {
let seconds: TimeInterval = Double(hours) * 60 * 60
let newDate: Date = self.addingTimeInterval(seconds)
return newDate
}
}
call this function as Date().addHours(1)
To get specific time of current date
func getDateFromHour(hour: Int) -> Date {
let date = Date()
let calendar = Calendar.current
et componentsCurrent = calendar.dateComponents([.year, .month, .day], from: date)
var components = DateComponents()
components.hour = hour
components.minute = 0
components.second = 0
components.month = componentsCurrent.month
components.day = componentsCurrent.day
components.year = componentsCurrent.year
return calendar.date(from: components)!
}
Note: you should use 24-hour clock while passing the parameter hour.

How to find the time span between two times?

I want to calculate a remaining time. I have a finish time. How can I calculate the time remaining between now and finish time?
I need something like that
let date = NSDate()
let formatter = NSDateFormatter()
formatter.timeStyle = .ShortStyle
var now = formatter.stringFromDate(date) //prints 12.21 AM
var finishTime = "13:30 PM"
var remaining = now - finishTime //I want it to print 01:09 as remaining time
func timeRemainingString(finishDate date:NSDate) -> String {
let secondsFromNowToFinish = date.timeIntervalSinceNow
let hours = Int(secondsFromNowToFinish / 3600)
let minutes = Int((secondsFromNowToFinish - Double(hours) * 3600) / 60)
let seconds = Int(secondsFromNowToFinish - Double(hours) * 3600 - Double(minutes) * 60 + 0.5)
return String(format: "%02d:%02d:%02d", hours, minutes, seconds)
}
The correct and ultimately much simpler solution, and handles localization and things like leap seconds / days properly, is to use NSDateComponentsFormatter.
let formatter = DateComponentsFormatter()
formatter.zeroFormattingBehavior = .pad
formatter.allowedUnits = [.hour, .minute, .second]
print(formatter.string(from: 200.0)!)
Outputs "0:03:20"
This is a Swift version of this Objective C answer.
There are lots of different options that you can see in the documentation in case you want something more like "About 3 seconds remaining", abbreviations, more units like years/months/days etc.