Compare Date and find hour, minutes and seconds.

DateComponent.swift

//First find a new instance of Date, and get current Calendar details. Now as per our needs we need to find components. In most case we use hour, minute and second. However there are full list of Calendar components like era, year, month, day, hour, minute, second, weekday, weekdayOrdinal, quarter, weekOfMonth, weekOfYear, yearForWeekOfYear, nanosecond, calendar and timeZone
//To get values of hour, minute and second we need to add following code.

let date = Date()
let calendar = Calendar.current
let hour = calendar.component(.hour, from: date)
let minute = calendar.component(.minute, from: date)
let second = calendar.component(.second, from: date)
print("\(hour):\(minute):\(second)")


//Find difference between two dates using calendar

var compos:Set<Calendar.Component> = Set<Calendar.Component>()
compos.insert(.minute)
let difference = calendar.dateComponents(compos, from: oldDate, to: Date())
if let minutediff = difference.minute {
    print(minutediff)  
  }
}