TimeInterval's in() function must accept or not a reference date

[ernestofndz]

Hey guys, amazing work, love it.

I've got a weird behaviour when comparing dates. I'm running the latest version at this moment which is 4.4.2

Date base that I'm using to compare
2017-11-21 00:00:00 +0000 timeIntervalSince1970 = 1511222400.0

Against
2017-11-30 00:00:00 +0000 timeIntervalSince1970 = 1512000000.0
difference in seconds is 777600 which in days is 9
SwiftDate says 9 ✅

Against
2017-12-01 00:00:00 +0000 timeIntervalSince1970 = 1512086400.0
difference in seconds is 864000 which in days is 10
SwiftDate says 9 ❎

Dates going forward are also calculated wrong. Any ideas?

[malcommac]

Hi @ernestofndz , may I ask to post the code used for these test here so I can make further investigations? Thanks

[ernestofndz]

Hi @malcommac, I just created a sample project: https://github.com/ernestofndz/SDDateDiff.

The code in the AppDelegate makes no difference, but just keeping it as I have in the other project. If I get some time this weekend will try to take a look myself. Thanks!

[malcommac]

Thank you for your report.
Function return wrong values because conversion take care of the interval starting from a specific date (specifically range used by the function is {Date() - Date() - interval}).
I've modified the function to allow passing a start reference date.
If date is passed conversion take care of this value.
If date is not passed conversion is absolute but only a small subset of time components are accepted (.day,.hour,.minute,.second).

/// Express given time interval in other time units.
/// If a reference date (`fromDate`) is not specified conversion is aware of day light saving times and other possible nasty things
/// (only `.day,.hour,.minute,.second` are supported as components).
/// If a reference date is specified conversion is made using the interval from passed reference date and include calendar/date
/// specific events.
///
///
/// - Parameters:
///   - components: components to extract
///   - date: reference date; `nil` uses absolute conversion, valida date to set the interval from a specific date.
///   - calendar: context calendar; `nil` uses `Date.DefaultRegion.calendar` instead
/// - Returns: components
public func `in`(_ components: [Calendar.Component], fromDate date: Date? = nil, of calendar: Calendar? = nil) -> [Calendar.Component : Int] {
	guard let refDate = date else {
			// Absolute conversion, not taking care of specific starting date
		let days = Int( (components.contains(.day) ? self / (60 * 60 * 24) : 0) )
		let hours = Int((components.contains(.hour) ? ((self / (60 * 60)) - (Double(days) * 24)) : 0))
		let minutes = Int( (components.contains(.minute) ? ((self / 60) - (Double(days) * 24 * 60) - (Double(hours) * 60)) : 0))
		let seconds = Int( (components.contains(.second) ? (self - (Double(days) * 24 * 60) - (Double(hours) * 60 * 60) - Double(minutes) * 60) : 0))
			
		var components: [Calendar.Component : Int] = [:]
		if (days != 0) 		{ components[.day] = Int(days) }
		if (hours != 0) 	{ components[.hour] = Int(hours) }
		if (minutes != 0)	{ components[.minute] = Int(minutes) }
		if (seconds != 0)	{ components[.second] = Int(seconds) }
		return components
	}
		
	let cal = calendar ?? Date.defaultRegion.calendar
	let dateFrom: Date = refDate
	let dateTo: Date = dateFrom.addingTimeInterval(self)
	let cmps = cal.dateComponents(componentsToSet(components), from: dateFrom, to: dateTo)
	return cmps.toComponentsDict()
}