Get unavailable date in a datepicker (Swift) - swift

Question

I have a UIDatePicker which is available for days from today to the next week ( from Date() to Date().day + 7 ).
Suppose that today is 30th day of the month, so the available days to choose are 30th day of this month and first to 6th day of next month.
In this case, I need to change the datePicker month to next month as the user change day from 30 to 1.
But the problem is:
"When I change the day to an invalid one, the .change method give me the least valid day."
Example:
Assumptions:
Today = 28 July.
Choosable dates = 28 July to 3 August.
What I need:
User can not choose the days before 28 July and not after 3 August.
When user wants to change day to 1, 2 or 3 August, the datePicker itself change the month to August and make 1, 2 and 3 available to
be chosen by user.
Main Problem
When user change the day to 1, 2 or 3, I can not get the 1, 2 or 3! and it returns me "28"!

Answer 1

Just set maximumDate property of your UIDatePicker to desired date.
func setupDatePicker(){
var currDateComponents = getDateComponents(fromDate: Date())
var maxDateComponents = currDateComponents
if let date = currDateComponents?.day{
maxDateComponents?.day = date + 7
}
self.datePicker?.maximumDate = getDate(fromDateComponents: maxDateComponents)
}
func getDateComponents(fromDate date: Date?)-> DateComponents?{
let calendar = Calendar(identifier: .gregorian)
var dateComponents: DateComponents? = nil
if(date != nil){
dateComponents = calendar.dateComponents([.day, .month, .year], from: date!)
}
return dateComponents
}
func getDate(fromDateComponents dateComponents:DateComponents?)-> Date?{
let calendar = Calendar(identifier: .gregorian)
if let componentsBasedDate = calendar.date(from: dateComponents!) {
return componentsBasedDate
}
return nil
}

Answer 2

Call this function in viewDidLoad to setup calendar for setting maximum and minimum date:
fileprivate func setupCalendar() {
datePicker.minimumDate = Calendar.current.date(byAdding: .day, value: 0, to: ServerTime.sharedInstance.nowTime)
datePicker.maximumDate = Calendar.current.date(byAdding: .day, value: +7, to: ServerTime.sharedInstance.nowTime)
}
for calculate days between shown date and current date I've used this method:
extension Date {
//Calculate days between two day objects
func daysBetween(_ date: Date) -> Int {
let calendar = NSCalendar.current
// Replace the hour (time) of both dates with 00:00
let date1 = calendar.startOfDay(for: date)
let date2 = calendar.startOfDay(for: self)
let components = calendar.dateComponents([.day], from: date1, to: date2)
return components.day ?? 0 // This will return the number of day(s) between dates
}
}}

Answer 3

In fact, it is impossible to get date before they chose. And according to unavailability of days in next month before changing the month, I can not use UIDatePicker to handle it.
So Finally I implemented my custom UIPickerView.
as #holex said.
Thank you all for answering.