ios - Swift:向按钮添加渐变后按钮图像不显示

Question

请帮忙，我已经创建了一个渐变，我已经添加到一个按钮，但现在我使用 Storyboard 设置的按钮图像不再显示。我的代码如下:

import UIKit

class MenuViewController: UIViewController {

    @IBOutlet weak var productsAndServicesButton: UIButton!

       override func viewDidLoad() {
        super.viewDidLoad()

        let bg = CAGradientLayer().redBackgroundGradient()
        bg.frame = self.productsAndServicesButton.bounds
        self.productsAndServicesButton.layer.insertSublayer(bg, at: 0)

   }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }



}

实际实现渐变的带函数代码如下:

import UIKit

extension CAGradientLayer {

    func redBackgroundGradient() -> CAGradientLayer{
        let startColor =  UIColor(red:0.82, green:0.13, blue:0.19, alpha:1.0)
        let centreColor = UIColor(red:0.65, green:0.04, blue:0.10, alpha:1.0)
        let endColor = UIColor(red:0.56, green:0.04, blue:0.09, alpha:1.0)

        let gradientColors : [CGColor] = [startColor.cgColor,centreColor.cgColor,endColor.cgColor]
        let gradientLocations : [Float] = [0.0,0.5,1.0]
        let gradientLayer : CAGradientLayer = CAGradientLayer()
        gradientLayer.colors = gradientColors
        gradientLayer.locations = gradientLocations as [NSNumber]?

        return gradientLayer
    }


}

我希望图像出现在渐变之上，如下所示

the red will be the gradient and the white image is the one i want to display

Answer 1

您可以使用 bring​Subview(to​Front:​) 将按钮的 imageView 移动到 顶部位置

if let imageView = button.imageView {
    productsAndServicesButton.bringSubviewToFront(imageView)
}