Check if date is in coming month

Question

I'm setting a date to a certain birthdayTextField like so

@objc func birthdayDatePickerValueChanged(sender: UIDatePicker) {
    let formatter = DateFormatter()
    formatter.dateStyle = .medium
    formatter.timeStyle = .none
    birthdayTextField.text = formatter.string(from: sender.date)

}

Now this textfield value is stored in coredata in a string attribute. There can be many such birthday dates stored in coredata. Now when I fetch these dates from the database, I want to show in a tableview only those dates which come in the following month.

How can it be achieved...?

Answer 1

This is a solution using the powerful date math abilities of Calendar together with DateComponents in a Date extension.

• It calculates the first day of next month with nextDate(after:matching:matchingPolicy:) looking for day == 1
• It compares the given date with the first date of next month to the month granularity with compare(:to:toGranularity:).

---

extension Date {
    func isDateInNextMonth() -> Bool {
        let calendar = Calendar.current
        let nextMonth = calendar.nextDate(after: Date(), matching: DateComponents(day:1), matchingPolicy: .nextTime)!
        return calendar.compare(self, to: nextMonth, toGranularity: .month) == .orderedSame
   }
}

Use it simply in your method

sender.date.isDateInNextMonth()

---

Or – more versatile – according to the other isDateIn... methods as extension of Calendar

extension Calendar {
    func isDateInNextMonth(_ date : Date) -> Bool {
        let nextMonth = self.nextDate(after: Date(), matching: DateComponents(day:1), matchingPolicy: .nextTime)!
        return self.compare(date, to: nextMonth, toGranularity: .month) == .orderedSame
    }
}

and use it

Calendar.current.isDateInNextMonth(sender.date)

---

Edit:

If you want to check if the date is in the next 30 days it's still easier

extension Calendar {
    func isDateInNextThirtyDays(_ date : Date) -> Bool {
        return self.dateComponents([.month], from: Date(), to:date).month! < 1
    }
}