Week numbers in Swift

To do week number calculations in Swift, you need configure a Calendar instance.

var calendar = Calendar(identifier: .gregorian) calendar.firstWeekday = 2 calendar.minimumDaysInFirstWeek = 4

How to get the week number from a date

To get the ISO week number (1-53), use calendar.component(.weekOfYear, from: date).

To get the corresponding four-digit year (e.g. 2013), use calendar.component(.yearForWeekOfYear, from: date).

date is a Date instance.

Read more about component() in the Swift documentation.