swift - UISegmentedControl iOS 13 clear color

Question

On iOS 12, to get a UISegmentedControl with clear border, clear divider line, everything clear was easy. All I did was this:

  settingControl.tintColor = .clear

   let font = myFont
   let boldfont = myBoldFont

  settingControl.setTitleTextAttributes([NSAttributedString.Key.foregroundColor : UIColor.white, NSAttributedString.Key.font:font], for: .normal)
  settingControl.setTitleTextAttributes([NSAttributedString.Key.foregroundColor : UIColor.red, NSAttributedString.Key.font:boldfont], for: .selected)

And then UISegmentedControl was full clear color (divider line, background, border)

But in iOS 13, I can not get it fully clear. I can set

settingControl.selectedSegmentTintColor = UIColor.clear

But it still does not clear the backgroundColor and divider line.

I tried setting backgroundColor to clear, but no effect.

 settingControl.backgroundColor = UIColor.clear

I also tried setting a clear image but still nothing:

 public extension UIImage {

  /**
   Returns image with size 1x1px of certain color.
   */
 class func imageWithColor(color : UIColor) -> UIImage? {
    let rect = CGRect(x: 0, y: 0, width: 1, height: 1)
    UIGraphicsBeginImageContext(rect.size)
    let context = UIGraphicsGetCurrentContext()

    context?.setFillColor(color.cgColor)

    context?.fill(rect)

    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return image
}

 }

And then this:

  let clearImage = UIImage.imageWithColor(color: UIColor.clear)
    settingControl.setDividerImage(clearImage, forLeftSegmentState: .normal, rightSegmentState: .normal, barMetrics: .default)


   settingControl.setBackgroundImage(clearImage, for: .normal, barMetrics: .default)
   settingControl.setBackgroundImage(clearImage, for: .selected, barMetrics: .default)

This is how it looks like on iOS 12. On iOS 13, this seems impossible.

Answer 1

Here's a way to replicate that plain segmented control in iOS 13:

import UIKit
import PlaygroundSupport

class PlainSegmentedControl: UISegmentedControl {
    override init(items: [Any]?) {
        super.init(items: items)

        setup()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // Used for the unselected labels
    override var tintColor: UIColor! {
        didSet {
            setTitleTextAttributes([.foregroundColor: tintColor!, NSAttributedString.Key.font: UIFont.systemFont(ofSize: 13, weight: .regular)], for: .normal)
        }
    }

    // Used for the selected label
    override var selectedSegmentTintColor: UIColor? {
        didSet {
            setTitleTextAttributes([.foregroundColor: selectedSegmentTintColor ?? tintColor!, NSAttributedString.Key.font: UIFont.systemFont(ofSize: 13, weight: .regular)], for: .selected)
        }
    }

    private func setup() {
        backgroundColor = .clear

        // Use a clear image for the background and the dividers
        let tintColorImage = UIImage(color: .clear, size: CGSize(width: 1, height: 32))
        setBackgroundImage(tintColorImage, for: .normal, barMetrics: .default)
        setDividerImage(tintColorImage, forLeftSegmentState: .normal, rightSegmentState: .normal, barMetrics: .default)

        // Set some default label colors
        setTitleTextAttributes([.foregroundColor: UIColor.black, NSAttributedString.Key.font: UIFont.systemFont(ofSize: 13, weight: .regular)], for: .normal)
        setTitleTextAttributes([.foregroundColor: tintColor!, NSAttributedString.Key.font: UIFont.systemFont(ofSize: 13, weight: .regular)], for: .selected)
    }
}

Here's some test code to put in a playground:

// Create a dark green view as a test background
let bg = UIView(frame: CGRect(x: 0, y: 0, width: 400, height: 100))
bg.backgroundColor = UIColor(red: 0.224, green: 0.408, blue: 0.467, alpha: 1)

// The plain segmented control
let seg = PlainSegmentedControl(items: ["Number One", "Number Two", "Number Three"])
seg.tintColor = .white
seg.selectedSegmentTintColor = .green
seg.selectedSegmentIndex = 0
bg.addSubview(seg)
PlaygroundPage.current.liveView = bg

Here's the UIImage extension to create a sized image from a color:

extension UIImage {
    convenience init(color: UIColor, size: CGSize) {
        UIGraphicsBeginImageContextWithOptions(size, false, 1)
        color.set()
        let ctx = UIGraphicsGetCurrentContext()!
        ctx.fill(CGRect(origin: .zero, size: size))
        let image = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()

        self.init(data: image.pngData()!)!
    }
}