A Swift struct for a Clock.

Clock.swift

//You can get the time components, but can only increment 1 second at a time.

struct Clock {

    var seconds: Int = 0 {
        didSet {
            if seconds == 60 {
                minutes += 1
                seconds = 0
            }
        }
    }

    private(set) var minutes: Int = 0 {
        didSet {
            if minutes == 60 {
                hours += 1
                minutes = 0
            }
        }
    }

    private(set) var hours: Int = 0

    mutating func increment() {
        seconds += 1
    }

}