NSDate beginning of day and end of day

Question

Start Of Day / End Of Day — Swift 4

  // Extension

extension Date {
    var startOfDay: Date {
        return Calendar.current.startOfDay(for: self)
    }

    var endOfDay: Date {
        var components = DateComponents()
        components.day = 1
        components.second = -1
        return Calendar.current.date(byAdding: components, to: startOfDay)!
    }

    var startOfMonth: Date {
        let components = Calendar.current.dateComponents([.year, .month], from: startOfDay)
        return Calendar.current.date(from: components)!
    }

    var endOfMonth: Date {
        var components = DateComponents()
        components.month = 1
        components.second = -1
        return Calendar.current.date(byAdding: components, to: startOfMonth)!
    }
}

// End of day = Start of tomorrow minus 1 second
// End of month = Start of next month minus 1 second

Swift 5 Simple and more precise answer.

Start time: 00:00:00

End time: 23:59:59.5

let date = Date() // current date or replace with a specific date
let calendar = Calendar.current
let startTime = calendar.startOfDay(for: date)
let endTime = calendar.date(bySettingHour: 23, minute: 59, second: 59, of: date)

Extra

let yesterday = Calendar.current.date(byAdding: .day, value: -1, to: noon)!
let tomorrow = Calendar.current.date(byAdding: .day, value: 1, to: noon)!
let specificDate = Date("2020-01-01")

extension Date {
    init(_ dateString:String) {
        let dateStringFormatter = DateFormatter()
        dateStringFormatter.dateFormat = "yyyy-MM-dd"
        dateStringFormatter.locale = NSLocale(localeIdentifier: "en_US_POSIX") as Locale
        let date = dateStringFormatter.date(from: dateString)!
        self.init(timeInterval:0, since:date)
    }
}

You are missing NSDayCalendarUnit in

NSDateComponents *components = [cal components:( NSMonthCalendarUnit | NSYearCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit ) fromDate:date];

In iOS 8+ this is really convenient; you can do:

let startOfDay: Date = Calendar.current.startOfDay(for: Date())

To get the end of day then just use the Calendar methods for 23 hours, 59 mins, 59 seconds, depending on how you define end of day.

// Swift 5.0
let components = DateComponents(hour: 23, minute: 59, second: 59)
let endOfDay = Calendar.current.date(byAdding: components, to: startOfDay)

Date Math

Apple iOS NSCalendar Documentation. (See Section: Calendrical Calculations)

NSCalendar methods discussed by NSHipster.

My Swift extensions for NSDate:

Swift 1.2

extension NSDate {

    func beginningOfDay() -> NSDate {
        var calendar = NSCalendar.currentCalendar()
        var components = calendar.components(.CalendarUnitYear | .CalendarUnitMonth | .CalendarUnitDay, fromDate: self)
        return calendar.dateFromComponents(components)!
    }

    func endOfDay() -> NSDate {
        var components = NSDateComponents()
        components.day = 1
        var date = NSCalendar.currentCalendar().dateByAddingComponents(components, toDate: self.beginningOfDay(), options: .allZeros)!
        date = date.dateByAddingTimeInterval(-1)!
        return date
    }
}

Swift 2.0

extension NSDate {

    func beginningOfDay() -> NSDate {
        let calendar = NSCalendar.currentCalendar()
        let components = calendar.components([.Year, .Month, .Day], fromDate: self)
        return calendar.dateFromComponents(components)!
    }

    func endOfDay() -> NSDate {
        let components = NSDateComponents()
        components.day = 1
        var date = NSCalendar.currentCalendar().dateByAddingComponents(components, toDate: self.beginningOfDay(), options: [])!
        date = date.dateByAddingTimeInterval(-1)
        return date
    }
}