我也有同样的问题，但没有很酷的方法来解决它。所以我做了这个小的变通办法。我不喜欢它，我也不为此感到自豪，但它的工作。

func fixBackgroundSegmentControl( _ segmentControl: UISegmentedControl){
    if #available(iOS 13.0, *) {
        //just to be sure it is full loaded
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { 
            for i in 0...(segmentControl.numberOfSegments-1)  {
                let backgroundSegmentView = segmentControl.subviews[i]
                //it is not enogh changing the background color. It has some kind of shadow layer 
                backgroundSegmentView.isHidden = true 
            }
        }
    }
}

我找到了最简单的解决办法。

let segmentControl: UISegmentControl = ... 
segmentControl.subviews.forEach { subview in
  subview.backgroundColor = .white
}

为我工作（斯威夫特5）。

let background = myColors.background
let selectedColor = myColors.foreground

if #available(iOS 13.0, *)
{
    segmentedControl.tintColor = background
    segmentedControl.backgroundColor = background
    segmentedControl.selectedSegmentTintColor = selectedColor
    segmentedControl.setTitleTextAttributes([.foregroundColor: selectedColor as Any], for: .normal)
    segmentedControl.setTitleTextAttributes([.foregroundColor: background as Any], for: .selected)
}
else
{
    segmentedControl.tintColor = background
    segmentedControl.backgroundColor = selectedColor
    segmentedControl.layer.cornerRadius = 4
}

SWIFT 3和4+
从这个答案https://stackoverflow.com/a/31652184/3249196，如果你想要一个没有灰色覆盖的全白色背景，只需将tintColor和backgroundColor替换为UIColor.white

extension UISegmentedControl {
    func removeBorders() {
        setBackgroundImage(imageWithColor(color: backgroundColor!), for: .normal, barMetrics: .default)
        setBackgroundImage(imageWithColor(color: tintColor!), for: .selected, barMetrics: .default)
        setDividerImage(imageWithColor(color: UIColor.clear), forLeftSegmentState: .normal, rightSegmentState: .normal, barMetrics: .default)
    }

    // create a 1x1 image with this color
    private func imageWithColor(color: UIColor) -> UIImage {
        let rect = CGRect(x: 0.0, y: 0.0, width:  1.0, height: 1.0)
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()
        context!.setFillColor(color.cgColor);
        context!.fill(rect);
        let image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        return image!
    }
}

可接受的答案可以简化，我们可以通过子类化UISegmentedControl并重写layoutSubviews方法来避免使用DispatchQueue.main.async调用：

class SegmentedControl: UISegmentedControl {
  override func layoutSubviews() {
    super.layoutSubviews()
    for i in 0...(numberOfSegments - 1)  {
      subviews[i].isHidden = true
    }
  }
}

我完成了前一个答案的代码，一切都为我工作

extension UISegmentedControl {

    func applyWhiteBackgroundColor() {
        // for remove bottom shadow of selected element
        self.selectedSegmentTintColor = selectedSegmentTintColor?.withAlphaComponent(0.99)
        if #available(iOS 13.0, *) {
            //just to be sure it is full loaded
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
                guard let self = self else {
                    return
                }
                for i in 0 ..< (self.numberOfSegments)  {
                    let backgroundSegmentView = self.subviews[i]
                    //it is not enogh changing the background color. It has some kind of shadow layer
                    backgroundSegmentView.isHidden = true
                }
            }
        }
    }
}

}
Modified Segmented Control

在Xamarin.iOS中，这对我很有效：

class MySegmentedControl : UISegmentedControl
{
    int insertedIndex = 0;

    public override void InsertSubview(UIView view, nint atIndex)
    {
        base.InsertSubview(view, atIndex);

        if (insertedIndex == 2 || insertedIndex == 3)
            view.Hidden = true;

        insertedIndex++;
    }
}