I want to get the current week start and end date and I also want to use the previous week start and end date and next week of the start and end date in current month.
Here is a solution for the swift4, we can get all the days for the current week.
var calendar = Calendar(identifier: Calendar.Identifier.gregorian)
let today = calendar.startOfDay(for: Date())
let dayOfWeek = calendar.component(.weekday, from: today) - calendar.firstWeekday
let weekdays = calendar.range(of: .weekday, in: .weekOfYear, for: today)!
let days = (weekdays.lowerBound ..< weekdays.upperBound)
.flatMap { calendar.date(byAdding: .day, value: $0 - dayOfWeek, to: today) }