Swift, Date, Calendar

let year = 2019
let month = 7

let nowDate:Date = Date()
let calendar = Calendar.current
let date = calendar.date(from: DateComponents(year: year, month: month, day: 1,
                                                   hour: 12, minute: 0, second: 0))

let weekOfFirstDay = Calendar.current.component(.weekday, from: date!)
// sunday = 1, saturday = 7


let toLastDay = DateComponents(month: 1, day: -1)
let endOfMonth = calendar.date(byAdding: toLastDay, to: date!)
let lastday = calendar.component(.day, from: endOfMonth!)



let format = DateFormatter()
format.dateFormat = "yyyy-MM-dd HH:mm:ss"
let formattedDate = format.string(from: date!)
let nowDateFormatted = format.string(from: nowDate)

NSLog(formattedDate)
NSLog(nowDateFormatted)

NSLog("yearMonth = \(year).\(month)")
NSLog("firstWeekDay = \(weekOfFirstDay)")
NSLog("end of month = \(lastday)")