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This topic provides you a walkthrough to creating a custom date picker using the C1DropDown control. For this, you begin by creating an iOS application, and initializing a C1DropDown, a C1Calendar control, and a C1MaskedTextField control. To create a date picker, you need to set the Header property to the object of the MaskedTextField and DropDown property to the object of the C1Calendar class.
The image below shows how a custom date picker created using the C1DropDown appears.

Add the following code to your ViewController to display the control.
public static C1MaskedTextField maskedField;
public C1Calendar calendar;
public static C1DropDown d;
public C1DropDown DropDown;
public override void ViewDidLoad()
{
base.ViewDidLoad();
DropDown.DropDownHeight = 300;
DropDown.DropDownWidth = DropDown.Frame.Size.Width;
DropDown.DropDownMode = DropDownMode.ForceBelow;
DropDown.IsAnimated = true;
C1MaskedTextField maskedField = new C1MaskedTextField();
maskedField.Mask = "00/00/0000";
maskedField.BackgroundColor = UIColor.Clear;
maskedField.BorderStyle = UITextBorderStyle.None;
DropDown.Header = maskedField;
C1Calendar calendar = new C1Calendar();
calendar.SelectionChanged += (object sender, CalendarSelectionChangedEventArgs e) =>
{
DateTime dateTime = calendar.SelectedDates[0];
string strDate = dateTime.ToString("MM-dd-yyyy");
maskedField.Text = strDate;
};
DropDown.DropDown = calendar;
this.View.Add(DropDown);
}