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

更新:

使用UIButtonBackgroundColor Swift库。

OLD:

使用下面的帮助工具创建一个1px x 1px的图像，灰度填充颜色:

UIImage *image = ACUTilingImageGray(248/255.0, 1);

或RGB填充颜色:

UIImage *image = ACUTilingImageRGB(253/255.0, 123/255.0, 43/255.0, 1);

然后，使用该图像设置按钮的背景图像:

[button setBackgroundImage:image forState:UIControlStateNormal];

助手

#pragma mark - Helpers

UIImage *ACUTilingImageGray(CGFloat gray, CGFloat alpha)
{
    return ACUTilingImage(alpha, ^(CGContextRef context) {
        CGContextSetGrayFillColor(context, gray, alpha);
    });
}

UIImage *ACUTilingImageRGB(CGFloat red, CGFloat green, CGFloat blue, CGFloat alpha)
{
    return ACUTilingImage(alpha, ^(CGContextRef context) {
        CGContextSetRGBFillColor(context, red, green, blue, alpha);
    });
}

UIImage *ACUTilingImage(CGFloat alpha, void (^setFillColor)(CGContextRef context))
{
    CGRect rect = CGRectMake(0, 0, 0.5, 0.5);
    UIGraphicsBeginImageContextWithOptions(rect.size, alpha == 1, 0);
    CGContextRef context = UIGraphicsGetCurrentContext();
    setFillColor(context);
    CGContextFillRect(context, rect);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

注意:ACU是我的Cocoa Touch静态库称为Acani Utilities的类前缀，其中AC是Acani, U是Utilities。

你可以使用这个类别添加方法setBackgroundColor:forState:

https://github.com/damienromito/UIButton-setBackgroundColor-forState-

UIButton扩展与Swift 3+语法:

extension UIButton {
    func setBackgroundColor(color: UIColor, forState: UIControlState) {
        UIGraphicsBeginImageContext(CGSize(width: 1, height: 1))
        UIGraphicsGetCurrentContext()!.setFillColor(color.cgColor)
        UIGraphicsGetCurrentContext()!.fill(CGRect(x: 0, y: 0, width: 1, height: 1))
        let colorImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        self.setBackgroundImage(colorImage, for: forState)
    }}

像这样使用它:

YourButton.setBackgroundColor(color: UIColor.white, forState: .highlighted)

最初的回答: https://stackoverflow.com/a/30604658/3659227

斯威夫特3:

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, forUIControlState state: UIControlState) {
        self.setBackgroundImage(imageWithColor(color: color), for: state)
    }
}

你可以通过简单地使用UIButton上的setBackgroundImage方法，并使用这个UIImage(color:)初始化项来使用一张图像，像这样轻松地更改高亮显示/选中的按钮背景颜色:

btn.setBackgroundImage(UIImage(color: .black), for: .highlighted)

注意:

如果你为圆角边框使用cornerRadius属性，你必须将clipsToBounds设置为true，这样所选的背景颜色将保留圆角半径值。