Swift 3 Easy way to truncate Date to start of the day/month/year

Question

Is there any easy way to truncate date like we can do in Oracle Database? For example, I need to set value starting from midnight. In Oracle I can do TRUNC(SYSDATE). But I canno

Answer 1

Calendar has dedicated methods:

• Start of the day

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

• Start of the month

    let now = Date()
    var startOfMonth = now
    var timeInterval : TimeInterval = 0.0
    Calendar.current.dateInterval(of: .month, start: &startOfMonth, interval: &timeInterval, for: now)
  
    print(startOfMonth)
  

• Start of the year

    let now = Date()
    var startOfYear = now
    var timeInterval : TimeInterval = 0.0
    Calendar.current.dateInterval(of: .year, start: &startOfYear, interval: &timeInterval, for: now)
  
    print(startOfYear)
  

Or as Date extension

extension Date {
    
    func startOf(_ dateComponent : Calendar.Component) -> Date {
        var calendar = Calendar.current
        calendar.timeZone = TimeZone(secondsFromGMT: 0)!
        var startOfComponent = self
        var timeInterval : TimeInterval = 0.0
        calendar.dateInterval(of: dateComponent, start: &startOfComponent, interval: &timeInterval, for: now)
        return startOfComponent
    }
}

let now = Date()

let startOfDay = now.startOf(.day)
let startOfMonth = now.startOf(.month)
let startOfYear = now.startOf(.year)

Regarding the time zone issue you can set the time zone of the current calendar accordingly.