Working Swiftly with NSTimeInterval

NSTimeInterval+Extension.swift

enum TimePeriod {
    case Seconds(Int)
    case Minutes(Int)
    case Hours(Int)
    
    var timeInterval: NSTimeInterval {
        switch self {
        case .Seconds(let value): return NSTimeInterval(value)
        case .Minutes(let value): return NSTimeInterval(value * 60)
        case .Hours(let value): return NSTimeInterval(value * 60 * 60)
        }
    }
}
extension Int {
    var seconds: TimePeriod { return .Seconds(self) }
    var minutes: TimePeriod { return .Minutes(self) }
    var hours: TimePeriod { return .Hours(self) }
}
extension NSTimeInterval {
    init(periods: TimePeriod...) {
        self = periods.reduce(0) { $0 + $1.timeInterval }
    }
}

Usage.swift

let time = NSTimeInterval(periods: .Hours(5), .Minutes(45))

//or using Int extension
let interval = NSTimeInterval(periods: 3.hours, 4.seconds)