How to get next sequence of array?-CodePudding

I have an array ["24-05-2022", "25-05-2022", "26-05-2022", "27-05-2022", "28-05-2022", "29-05-2022", "30-05-2022"], and two buttons as "Next"& "Previous". So now on clicking next button i need next 7 elements like ["31-05-2022", "01-06-2022", "02-06-2022", "03-06-2022", "04-06-2022", "05-06-2022", "06-06-2022"] then again clicking next button need next 7 ["07-06-2022 to "13-06-2022"] elements up to 10 times.

One clicking previous button I need previous 7 elements. So what should be the condition for the 'for loop'? I am getting next dates by using function below.

func getNextDates() {
    let formatter = DateFormatter()
    formatter.dateFormat = "dd-MM-YYYY"

    let selectedDate = self.presentDate

    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "dd-MM-yyyy"
    dateFormatter.timeZone = TimeZone(abbreviation: "GMT 0:00")
    guard let selected = dateFormatter.date(from: selectedDate) else {
        fatalError()
    }
    let dateString = formatter.string(from: selected)
    print("Selected Date is ==>",dateString)
    let calendar = Calendar(identifier: .gregorian)
    for i in 1...7 {
        let newDate = calendar.date(byAdding: .day, value: i, to: selected)
        let formatter = DateFormatter()
        formatter.dateFormat = "dd-MM-YYYY"
        let dateString = formatter.string(from: newDate!)
        
        print("Next DAYS ARE ==>>",dateString)
    }
}

I am able to get next dates once. But I want 10 times.

CodePudding user response：

Use the following code by creating an extension to the Date

var daysInCurrentWeek:[Date]?
let formatter = DateFormatter()

override func viewDidLoad() {
    super.viewDidLoad()
    formatter.dateFormat = "dd-MM-YYYY"
    
    daysInCurrentWeek = Date().daysOfWeek()
    let strings = daysInCurrentWeek?.map({formatter.string(from: $0)})
    print(strings)
}

@IBAction func nextButtonTapped(_ sender: UIButton) {
    let nextWeekdays = daysInCurrentWeek?.last?.byAdding(component: .weekOfMonth, value: 1)?.daysOfWeek()
    daysInCurrentWeek = nextWeekdays!
    print(nextWeekdays?.map({formatter.string(from: $0)}))
}

@IBAction func previousButtonTapped(_ sender: UIButton) {
    let previousWeekDays = daysInCurrentWeek?.last?.byAdding(component: .weekOfMonth, value: -1)?.daysOfWeek()
    daysInCurrentWeek = previousWeekDays
    print(previousWeekDays?.map({formatter.string(from: $0)}))
}

And the date extension will be like this

extension Date {
    func byAdding(component: Calendar.Component, value: Int, wrappingComponents: Bool = false, using calendar: Calendar = .current) -> Date? {
        calendar.date(byAdding: component, value: value, to: self, wrappingComponents: wrappingComponents)
    }
    func dateComponents(_ components: Set<Calendar.Component>, using calendar: Calendar = .current) -> DateComponents {
        calendar.dateComponents(components, from: self)
    }
    func startOfWeek(using calendar: Calendar = .current) -> Date {
        calendar.date(from: dateComponents([.yearForWeekOfYear, .weekOfYear], using: calendar))!
    }
    var noon: Date {
        Calendar.current.date(bySettingHour: 12, minute: 0, second: 0, of: self)!
    }
    func daysOfWeek(using calendar: Calendar = .current) -> [Date] {
        let startOfWeek = self.startOfWeek(using: calendar).noon
        return (0...6).map { startOfWeek.byAdding(component: .day, value: $0, using: calendar)! }
    }
}

Result will be like this

Optional(["12-06-2022", "13-06-2022", "14-06-2022", "15-06-2022", "16-06-2022", "17-06-2022", "18-06-2022"])
Optional(["05-06-2022", "06-06-2022", "07-06-2022", "08-06-2022", "09-06-2022", "10-06-2022", "11-06-2022"])
Optional(["29-05-2022", "30-05-2022", "31-05-2022", "01-06-2022", "02-06-2022", "03-06-2022", "04-06-2022"])
Optional(["05-06-2022", "06-06-2022", "07-06-2022", "08-06-2022", "09-06-2022", "10-06-2022", "11-06-2022"])
Optional(["12-06-2022", "13-06-2022", "14-06-2022", "15-06-2022", "16-06-2022", "17-06-2022", "18-06-2022"])
Optional(["19-06-2022", "20-06-2022", "21-06-2022", "22-06-2022", "23-06-2022", "24-06-2022", "25-06-2022"])
Optional(["26-06-2022", "27-06-2022", "28-06-2022", "29-06-2022", "30-06-2022", "01-07-2022", "02-07-2022"])
Optional(["03-07-2022", "04-07-2022", "05-07-2022", "06-07-2022", "07-07-2022", "08-07-2022", "09-07-2022"])
Optional(["10-07-2022", "11-07-2022", "12-07-2022", "13-07-2022", "14-07-2022", "15-07-2022", "16-07-2022"])