How to set the first day of current week to Tuesday in Swift?

问题:

How to set the first day of current week to Tuesday in Swift 3? The schedule will update every Tuesday so the first day have to start from Tuesday.

and then display on label :

thisWeekDate.text! = "\(first day of current week) - \(last day of current week)" 

Full code.

let today = NSDate()     let nextTue = Calendar.current.date(byAdding: .day, value: 6, to: today as Date)     let formatter = DateFormatter()     formatter.dateFormat = "yyyy-MM-dd"     let todayString = formatter.string(from: today as Date)     let nextString = formatter.string(from: nextTue!)     formatter.dateFormat = "dd-MMM-yyyy"      let calendar = NSCalendar(calendarIdentifier: NSCalendar.Identifier.gregorian)     let components = calendar!.components([.weekday], from: today as Date)      //Label code     thisWeekDate.text! = "\(first day of current week) - \(last day of current week)"      //If i can change the first day of current week this weekly update code can be deleted     if components.weekday == 3 {          print("Hello Tuesday")         thisWeekDate.text! = "\(todayString) - \(nextString)"          UserDefaults.standard.set(todayString, forKey: "todayStringKey")         _ = UserDefaults.standard.object(forKey: "todayStringKey") as? String         UserDefaults.standard.set(nextString, forKey: "nextStringKey")         _ = UserDefaults.standard.object(forKey: "nextStringKey") as? String      } else {         print("It's not Tuesday")         let RetrivedDate_1 = UserDefaults.standard.object(forKey: "todayStringKey") as? String         let RetrivedDate_2 = UserDefaults.standard.object(forKey: "nextStringKey") as? String          if let date_1 = RetrivedDate_1, let date_2 = RetrivedDate_2 {             thisWeekDate.text! = "\(date_1) - \(date_2)"         }       } 

App Design Screenshot

回答1:

Create a custom Gregorian calendar and set the first weekday to Tuesday

var customCalendar = Calendar(identifier: .gregorian) customCalendar.firstWeekday = 3 

Then you can get the week interval with

var startDate = Date() var interval = TimeInterval() customCalendar.dateInterval(of: .weekOfMonth, start: &startDate, interval: &interval, for: Date()) let endDate = startDate.addingTimeInterval(interval - 1) print(startDate, endDate) 

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