How to change the colors of a segment in a UISegmentedControl in iOS 13?

Question

A UISegmentedControl has a new appearance in iOS 13 and existing code to alter the colors of the segmented control no longer work as they did.

Prior to

Answer 1

Here is my take on Jonathan.'s answer for Xamarin.iOS (C#), but with fixes for image sizing. As with Cœur's comment on Colin Blake's answer, I made all images except the divider the size of the segmented control. The divider is 1xheight of the segment.

public static UIImage ImageWithColor(UIColor color, CGSize size)
{
    var rect = new CGRect(0, 0, size.Width, size.Height);
    UIGraphics.BeginImageContext(rect.Size);
    var context = UIGraphics.GetCurrentContext();
    context.SetFillColor(color.CGColor);
    context.FillRect(rect);
    var image = UIGraphics.GetImageFromCurrentImageContext();
    UIGraphics.EndImageContext();
    return image;
}

// https://stackoverflow.com/a/56465501/420175
public static void ColorSegmentiOS13(UISegmentedControl uis, UIColor tintColor, UIColor textSelectedColor, UIColor textDeselectedColor)
{
    if (!UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
    {
        return;
    }

    UIImage image(UIColor color)
    {
        return ImageWithColor(color, uis.Frame.Size);
    }

    UIImage imageDivider(UIColor color)
    {
        return ImageWithColor(color, 1, uis.Frame.Height);
    }

    // Must set the background image for normal to something (even clear) else the rest won't work
    //setBackgroundImage(UIImage(color: backgroundColor ?? .clear), for: .normal, barMetrics: .default)
    uis.SetBackgroundImage(image(UIColor.Clear), UIControlState.Normal, UIBarMetrics.Default);

    // setBackgroundImage(tintColorImage, for: .selected, barMetrics: .default)
    uis.SetBackgroundImage(image(tintColor), UIControlState.Selected, UIBarMetrics.Default);

    // setBackgroundImage(UIImage(color: tintColor.withAlphaComponent(0.2)), for: .highlighted, barMetrics: .default)
    uis.SetBackgroundImage(image(tintColor.ColorWithAlpha(0.2f)), UIControlState.Highlighted, UIBarMetrics.Default);

    // setBackgroundImage(tintColorImage, for: [.highlighted, .selected], barMetrics: .default)
    uis.SetBackgroundImage(image(tintColor), UIControlState.Highlighted | UIControlState.Selected, UIBarMetrics.Default);

    // setTitleTextAttributes([.foregroundColor: tintColor, NSAttributedString.Key.font: UIFont.systemFont(ofSize: 13, weight: .regular)], for: .normal)
    // Change: support distinct color for selected/de-selected; keep original font
    uis.SetTitleTextAttributes(new UITextAttributes() { TextColor = textDeselectedColor }, UIControlState.Normal); //Font = UIFont.SystemFontOfSize(13, UIFontWeight.Regular)
    uis.SetTitleTextAttributes(new UITextAttributes() { TextColor = textSelectedColor, }, UIControlState.Selected); //Font = UIFont.SystemFontOfSize(13, UIFontWeight.Regular)

    // setDividerImage(tintColorImage, forLeftSegmentState: .normal, rightSegmentState: .normal, barMetrics: .default)
    uis.SetDividerImage(imageDivider(tintColor), UIControlState.Normal, UIControlState.Normal, UIBarMetrics.Default);

    //layer.borderWidth = 1
    uis.Layer.BorderWidth = 1;

    //layer.borderColor = tintColor.cgColor
    uis.Layer.BorderColor = tintColor.CGColor;
}