Can I detect month change on UIDatePicker?

Question

I have a UIDatePicker with Inline style (showing as a calendar). I have an endpoint where I get the available dates for a month, so I would like to detect when the month that is showing is changed. I've tried all kinds of things, even add a target for the .allEvents event, but nothing seems to trigger it.

Is there a way to do that?

Answer 1

You should attach an IBAction to the valueChanged event for the picker.

(You could do that in Interface Builder, or by calling addTarget(_:action:for:) on the picker.)

That action will get called any time the user changes any part of the date. You'd then need to track the previous date and detect a change of month yourself.

Answer 2

If you're using a view model, you could easily handle this through that:

Run the below in a Playground to see what I mean:

final class ViewModel {

    var selectedDateChanged: ((Date) -> Void)?

    var selectedDate: Date {
        didSet {
            selectedDateChanged?(selectedDate)
        }
    }

    init(selectedDate: Date = .now) {
        self.selectedDate = selectedDate
    }
}

let viewModel = ViewModel()
viewModel.selectedDateChanged = { date in
    // now you have the fact that it changed
    // and the new value to use, checking the month
    print(date)
}

viewModel.selectedDate = .now