Time Comparisons in Swift

How do you compare just the time of a Date in Swift?

This is the route I took in the end, which makes it easy to compare just the time of a Date in swift

New Object Time:

class Time: Comparable, Equatable {
init(_ date: Date) {
    //get the current calender
    let calendar = Calendar.current

    //get just the minute and the hour of the day passed to it
    let dateComponents = calendar.dateComponents([.hour, .minute], from: date)

        //calculate the seconds since the beggining of the day for comparisions
        let dateSeconds = dateComponents.hour! * 3600 + dateComponents.minute! * 60

        //set the varibles
        secondsSinceBeginningOfDay = dateSeconds
        hour = dateComponents.hour!
        minute = dateComponents.minute!
    }

    init(_ hour: Int, _ minute: Int) {
        //calculate the seconds since the beggining of the day for comparisions
        let dateSeconds = hour * 3600 + minute * 60

        //set the varibles
        secondsSinceBeginningOfDay = dateSeconds
        self.hour = hour
        self.minute = minute
    }

    var hour : Int
    var minute: Int

    var date: Date {
        //get the current calender
        let calendar = Calendar.current

        //create a new date components.
        var dateComponents = DateComponents()

        dateComponents.hour = hour
        dateComponents.minute = minute

        return calendar.date(byAdding: dateComponents, to: Date())!
    }

    /// the number or seconds since the beggining of the day, this is used for comparisions
    private let secondsSinceBeginningOfDay: Int

    //comparisions so you can compare times
    static func == (lhs: Time, rhs: Time) -> Bool {
        return lhs.secondsSinceBeginningOfDay == rhs.secondsSinceBeginningOfDay
    }

    static func < (lhs: Time, rhs: Time) -> Bool {
        return lhs.secondsSinceBeginningOfDay < rhs.secondsSinceBeginningOfDay
    }

    static func <= (lhs: Time, rhs: Time) -> Bool {
        return lhs.secondsSinceBeginningOfDay <= rhs.secondsSinceBeginningOfDay
    }

    static func >= (lhs: Time, rhs: Time) -> Bool {
        return lhs.secondsSinceBeginningOfDay >= rhs.secondsSinceBeginningOfDay
    }

    static func > (lhs: Time, rhs: Time) -> Bool {
        return lhs.secondsSinceBeginningOfDay > rhs.secondsSinceBeginningOfDay
    }
}

Date Extension for easy access:
//Adds ability to just get the time from a date:

extension Date {
    var time: Time {
        return Time(self)
    }
}

Example:

let firstDate = Date()
let secondDate = firstDate

//Will return true
let timeEqual = firstDate.time == secondDate.time

Comparing Time in ios Swift

Compare the time by ignoring the date component -

func checkTime() -> Bool {

let dateFormatter: DateFormatter = DateFormatter()
dateFormatter.timeZone = TimeZone(abbreviation: "PKT")
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"

let startingSlot = "2000-01-01 08:00:00" //UTC
let endingSlot = "2000-01-01 23:00:00" //UTC

let date = Date()

let date1: Date = dateFormatter.date(from: startingSlot)!
let date2: Date = dateFormatter.date(from: endingSlot)!

let currentTime = 60*Calendar.current.component(.hour, from: date) + Calendar.current.component(.minute, from: date) + (Calendar.current.component(.second, from: date)/60) // in minutes
let time1 = 60*Calendar.current.component(.hour, from: date1) + Calendar.current.component(.minute, from: date1) + (Calendar.current.component(.second, from: date1)/60) // in minutes
let time2 =  60*Calendar.current.component(.hour, from: date2) + Calendar.current.component(.minute, from: date2) + (Calendar.current.component(.second, from: date1)/60) // in minutes

print(currentTime)
print(time1)
print(time2)

if(currentTime >= time1 && currentTime <= time2) {
    return true
} else {
    return false
}

}

Output-

1121

510

1410

true

comparing time without date swift3

Suggestion using DateComponents

Assuming this given array

let times = ["4:30 AM","1:00 PM","3:20 PM","6:40 PM","9:10 PM"]

Create a date formatter matching the format

let formatter = DateFormatter()
formatter.dateFormat = "h:mm a"

Map the time strings to Date and immediately to DateComponents considering only hour and minute

let dateArray = times.map { Calendar.current.dateComponents([.hour, .minute], from:formatter.date(from:$0)!) }

Map this array to the next date from now matching the components respectively

let upcomingDates = dateArray.map { Calendar.current.nextDate(after: Date(), matching: $0, matchingPolicy: .nextTime)!  }

Sort the array ascending, the first item is the date you are looking for
```
let nextDate = upcomingDates.sorted().first!
```
Use the formatter to convert the date back to a time string
```
print(formatter.string(from:nextDate))
```

Compare only time difference in Date objects

You can use Calendar to extract the DateComponents and then combine the day, month, and year from one with the hour, minute, and second of the other into another Date object. Then you can compare the two Date objects that share the same date using the well documented methods.

For example, given date1 and date2, we can calculate date3 with date of date1, but time of date2. We can then compare date1 to this new date3:

let calendar = Calendar.current
let components2 = calendar.dateComponents([.hour, .minute, .second], from: date2)
let date3 = calendar.date(bySettingHour: components2.hour!, minute: components2.minute!, second: components2.second!, of: date1)!

Then, to get the number of minutes between date1 and date3:

let minutes = calendar.dateComponents([.minute], from: date1, to: date3).minute!

Or hours and minutes:

let difference = calendar.dateComponents([.hour, .minute], from: date1, to: date3)
let hours = difference.hour!
let minutes = difference.minute!

Or, if you want to show this to the user, you'd often use DateComponentsFormatter to get a nice, localized string representation:

let formatter = DateComponentsFormatter()
formatter.unitsStyle = .full
formatter.allowedUnits = [.hour, .minute]  // or [.minute]
let string = formatter.string(from: date1, to: date3)!

Compare time duration values in Swift

You can use this String Extension to calculate total minutes from string

extension String {
    func getTimeInSeconds()-> Int? {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "mm:ss" //Your date format
        dateFormatter.timeZone = TimeZone.current //Current time zone
        var date = Date()
        if let getDate = dateFormatter.date(from: self) {//according to date format your date string
            date = getDate //Convert String to Date
        } else {
            dateFormatter.dateFormat = "hh:mm:ss"
            if let getDate = dateFormatter.date(from: self) {//according to date format your date string
                date = getDate //Convert String to Date
            } else {
                return nil
            }
        }
        
        let calendar = Calendar.current
        let components = calendar.dateComponents([.hour, .minute,.second], from: date)
        let hour = components.hour ?? 0
        let minute = components.minute ?? 0
        let seconds = components.second ?? 0
        return (hour * 360) + minute*60 + seconds
    }
}

You can use this extension like this

 let getSeconds = "01:20".getTimeInSeconds()

it will cover both formats mm:ss and hh:mm:ss and return seconds ... you can use these seconds to compare instead of string

Swift - Date String Compare

Here is a function that converts the given string to a date and compares it to the given dat (default today). By using startOfDay(for:) time is ignored in the comparison

func before(_ string: String, date: Date = Date()) -> Bool? {
    let locale = Locale(identifier: "en_US_POSIX")

    let dateFormatter = DateFormatter()
    dateFormatter.locale = locale
    dateFormatter.dateFormat = "MMM dd, yyyy"

    guard let inDate = dateFormatter.date(from: string) else {
        return nil
    }
    var calendar = Calendar.current
    calendar.locale = locale
    return inDate < calendar.startOfDay(for: date)
}

Time comparisons in swift

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)

Swift 3 - Comparing Date objects

I have tried this snippet (in Xcode 8 Beta 6), and it is working fine.

let date1 = Date()
let date2 = Date().addingTimeInterval(100)

if date1 == date2 { ... }
else if date1 > date2 { ... }
else if date1 < date2 { ... }

How can I compare times in an array?

Suppose we have this array:

let array = ["08:00", "23:00", "01:00", "04:00"]

A more convenient way of dealing with "bus times" would be to define a struct like so:

struct BusTime: Comparable, CustomStringConvertible {
    let hour    : Int
    let minute  : Int

    static func < (lhs: BusTime, rhs: BusTime) -> Bool {
        return (lhs.hour, lhs.minute) < (rhs.hour, rhs.minute)
    }

    var description: String {
        get {
            let formatter = NumberFormatter()
            formatter.minimumIntegerDigits = 2
            return formatter.string(for: hour)! + ":" + formatter.string(for: minute)!
        }
    }
}

N.B: In the rest of the answer I'll be force-unwrapping for brevity)

Let's create a sorted array of BusTimes:

let busTimes: [BusTime] = array.map { str in
    return BusTime(hour: Int(str.prefix(2))!, minute: Int(str.suffix(2))!)
}
var sortedBusTimes = busTimes.sorted()

Let's also define a variable nextBus which represents the next bus time:

var nextBus: BusTime = sortedBusTimes[0]

Now, let's create a time that corresponds to say the current date:

let nowComps = Calendar.current.dateComponents([.hour, .minute], from: Date())
let now = BusTime(hour: nowComps.hour!, minute: nowComps.minute!)

With binary search, we'll be able to find the next bus time in O(log(n)):

var low  = sortedBusTimes.startIndex
var high = sortedBusTimes.endIndex

while low < high {
    let middle = low + (high - low)/2      
    let middleTime = sortedBusTimes[middle]
    if middleTime == now {
        low = middle
        break
    } else if middleTime < now {
        low = middle + 1
    } else if now < middleTime {
        high = middle
    }
}

if low != sortedBusTimes.endIndex, high != 0 {
    nextBus = sortedBusTimes[low]
}

The definition middle could be simpler this way:

let middle = low + (high - low)/2

But take this article into consideration.

Finally, let's check:

print(nextBus)

At the time of writing this answer, it is 17:52. So the result printed in the console is:

23:00

Compare Date to String Date Value Swift

There is a better way to check if two dates are in the same day

let currentDate = Date()
let selectedDate = Date()
if Calendar.current.isDate(currentDate, inSameDayAs: selectedDate) {
    print("yes")
} else {
    print("no")
}