A UIPickerView with support for labels. Ported from http://blog.nottoobadsoftware.com/iphone-development/a-uipickerview-with-labels/

UILabeledPickerView.cs

[Register(nameof(UILabeledPickerView))]
public class UILabeledPickerView : UIPickerView
{
    public UILabeledPickerView(IntPtr handle) : base(handle)
    {

    }

    private IDictionary<int, string> mLabelsDictionary = new Dictionary<int, string>();

    /// <summary>
    /// Adds the label for the given component.
    /// </summary>
    public void SetLabel(string labeltext, int component)
    {
        mLabelsDictionary[component] = labeltext;
    }

    /// <summary>
    /// Adds the labels to the view, below the selection indicator glass-thingy.
    /// The labels are aligned to the right side of the wheel.
    /// The delegate is responsible for providing enough width for both the value and the label.
    /// </summary>
    public override void MovedToWindow()
    {
        // Exit if view is removed from the window or there are no labels.
        if (Window == null || !mLabelsDictionary.Any())
            return;

        var labelFont = UIFont.BoldSystemFontOfSize(20);

        // Find the width of all the wheels combined.
        var widthOfWheels = 0f;
        for (var i = 0; i < NumberOfComponents; i++)
        {
            widthOfWheels += (float)RowSizeForComponent(i).Width;
        }

        // Find the left side of the first wheel.
        // Seems like a misnomer, but that will soon be corrected.
        var rightSideOfWheel = (Frame.Size.Width - widthOfWheels) / 2;

        // Cycle through all wheels.
        for (var component = 0; component < NumberOfComponents; component++)
        {
            // Find the right side of the wheel.
            rightSideOfWheel += RowSizeForComponent(component).Width;

            // Get the text for the label.
            // Move on to the next if there is no label for this wheel.
            if (!mLabelsDictionary.ContainsKey(component))
                continue;

            var text = (NSString)mLabelsDictionary[component];

            // Set up the frame for the label.
            var frame = new CGRect
            {
                Size = text.StringSize(labelFont)
            };

            // Center it vertically.
            frame.Y = (Frame.Size.Height / 2) - (frame.Size.Height / 2) - 0.5f;

            // Align it to the right side of the wheel, with a margin.
            // Use a smaller margin for the rightmost wheel.
            frame.X = rightSideOfWheel - frame.Size.Width - (component == NumberOfComponents - 1 ? 5 : 7);

            // Set up the label.
            var label = new UILabel(frame)
            {
                Text = text,
                Font = labelFont,
                BackgroundColor = UIColor.Clear,
                ShadowColor = UIColor.White,
                ShadowOffset = new CGSize(0, 1)
            };

            // And now for the tricky bit: adding the label to the view.
            // Kind of a hack to be honest, might stop working if Apple decides to change the inner workings of the UIPickerView.
            if (ShowSelectionIndicator)
            {
                // if this is the last wheel, add label as the third view from the top
                if (component == NumberOfComponents - 1)
                    InsertSubview(label, Subviews.Length - 3);
                // otherwise add label as the 5th, 10th, 15th etc view from the top
                else
                    InsertSubviewAbove(label, Subviews.ElementAt(5 * (component + 1)));
            }
            else
                // there is no selection indicator, so just add it to the top
                AddSubview(label);
        }
    }
}