extension UIButton {
    func setBackgroundColor(color: UIColor, forState: UIControl.State) {
        let size = CGSize(width: 1, height: 1)
        UIGraphicsBeginImageContext(size)
        let context = UIGraphicsGetCurrentContext()
        context?.setFillColor(color.cgColor)
        context?.fill(CGRect(origin: CGPoint.zero, size: size))
        let colorImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        setBackgroundImage(colorImage, for: forState)
    }

}

谢谢@Maverick

class CustomButton: UIButton {

    override var isHighlighted: Bool {
        didSet {
            if (isHighlighted) {
                alpha = 0.5
            }
            else {
                alpha = 1
            }            
        }
    }

}

在Swift 5中

对于那些不想使用彩色背景击败所选状态的人

简单地说，你可以通过使用#Selector & if语句轻松地为每个状态单独更改UIButton颜色来解决这个问题

例如:

    override func viewDidLoad() {
    super.viewDidLoad()
    self.myButtonOutlet.backgroundColor = UIColor.white  //to reset the button color to its original color ( optionally )
}

@IBOutlet weak var myButtonOutlet: UIButton!{
    didSet{  // Button selector and image here
        self.myButtonOutlet.setImage(UIImage(systemName: ""), for: UIControl.State.normal)

        self.myButtonOutlet.setImage(UIImage(systemName: "checkmark"), for: UIControl.State.selected)



        self.myButtonOutlet.addTarget(self, action: #selector(tappedButton), for: UIControl.Event.touchUpInside)
    }
}

@objc func tappedButton() {  // Colors selection is here
    if self.myButtonOutlet.isSelected == true {

        self.myButtonOutlet.isSelected = false
        self.myButtonOutlet.backgroundColor = UIColor.white         
    } else {
        self.myButtonOutlet.isSelected = true

        self.myButtonOutlet.backgroundColor = UIColor.black
        self.myButtonOutlet.tintColor00 = UIColor.white

    }
}

extension UIButton {
    func setBackgroundColor(color: UIColor, forState: UIControl.State) {
        let size = CGSize(width: 1, height: 1)
        UIGraphicsBeginImageContext(size)
        let context = UIGraphicsGetCurrentContext()
        context?.setFillColor(color.cgColor)
        context?.fill(CGRect(origin: CGPoint.zero, size: size))
        let colorImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        setBackgroundImage(colorImage, for: forState)
    }

}

谢谢@Maverick

Swift中一个方便的通用扩展:

extension UIButton {
    private func imageWithColor(color: UIColor) -> UIImage {
        let rect = CGRectMake(0.0, 0.0, 1.0, 1.0)
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()

        CGContextSetFillColorWithColor(context, color.CGColor)
        CGContextFillRect(context, rect)

        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return image
    }

    func setBackgroundColor(color: UIColor, forUIControlState state: UIControlState) {
        self.setBackgroundImage(imageWithColor(color), forState: state)
    }
}

斯威夫特3.0

extension UIButton {
    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
    }

    func setBackgroundColor(_ color: UIColor, for state: UIControlState) {
        self.setBackgroundImage(imageWithColor(color: color), for: state)
    }
}

把它放进去，你就可以开始了: *属性可以在IB中设置，如果没有设置高亮背景，按下时背景不会改变

private var highlightedBackgroundColors = [UIButton:UIColor]()
private var unhighlightedBackgroundColors = [UIButton:UIColor]()
extension UIButton {

    @IBInspectable var highlightedBackgroundColor: UIColor? {
        get {
            return highlightedBackgroundColors[self]
        }

        set {
            highlightedBackgroundColors[self] = newValue
        }
    }

    override open var backgroundColor: UIColor? {
        get {
            return super.backgroundColor
        }

        set {
            unhighlightedBackgroundColors[self] = newValue
            super.backgroundColor = newValue
        }
    }

    override open var isHighlighted: Bool {
        get {
            return super.isHighlighted
        }

        set {
            if highlightedBackgroundColor != nil {
                super.backgroundColor = newValue ? highlightedBackgroundColor : unhighlightedBackgroundColors[self]
            }
            super.isHighlighted = newValue
        }
    }
}