leodabus

extension BidirectionalCollection where Iterator.Element == String, SubSequence.Iterator.Element == String {
    var sentence: String {
        guard let last = last else { return "" }
        return count <= 2 ? joined(separator: " and ") :
            dropLast().joined(separator: ", ") + " and " + last
    }
}

leodabus

extension Date {
    var year:    Int { return Calendar.autoupdatingCurrent.component(.year,   from: self) }
    var month:   Int { return Calendar.autoupdatingCurrent.component(.month,  from: self) }
    var day:     Int { return Calendar.autoupdatingCurrent.component(.day,    from: self) }
    var firstDayOfMonth: Date {
        return  Calendar.autoupdatingCurrent.date(from: DateComponents(year: year, month: month, day: 1))!
    }
    var lastDayOfMonth: Date {
        return  Calendar.autoupdatingCurrent.date(from: DateComponents(year: year, month: month+1, day: 0))!
    }