Calculating time difference using a colon

Question

Im trying to calculate the time difference between 18:00 & 06:00 and display the result in the same format. Both times are entered manually.

Answer 1

First create two NSDates from the string inputs and get the interval between the two then pass the interval through a formatting function we will create:

let date1:String = "12:00"
let date2:String = "13:00"

let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "HH:mm"
let date3 = dateFormatter.dateFromString(date1)
let date4 = dateFormatter.dateFromString(date2)

let interval = date4!.timeIntervalSinceDate(date3!)
print("\(stringFromTimeInterval(interval))")

now we need to format the interval which is the number of seconds between the two so create a function which returns a string:

func stringFromTimeInterval(interval: NSTimeInterval) -> String {
  let interval = Int(interval)
  let minutes = (interval / 60) % 60
  let hours = (interval / 3600)
  return String(format: "%02d:%02d", hours, minutes)
}

in your case you will set the date1 and date2 from I'm guessing the text fields in your program.