UITableView单元格在选择时突出显示，但UIImageView保持不透明。 如何突出显示整个单元格？

Question

The image is set on the imageView via a URL. When I do not set an image, the tablecell highlights just fine, but when the image is applied to it, it seems to become opaque, almost like the image has a higher z-index compared to the highlight view that the tablview is applying. Does this mean I will have to use a custom highlight?

Answer 1

When the cell is highlighted it sets the highlighted property of labels and images.

You need to provide a highlightedImage to the UIImageView or look at more complicated solutions.

Answer 2

Maybe a bit late for the party but this extension should work for your case.

It loads async an image from an URL and then create the corresponding highlighted image by using the default gray color. If you want you can change the overlay color by working on the fillcolor parameter.

extension UIImageView {
    func loadImage(url: String, placeHolder: UIImage?) {
        let anURL = URL(string: url)!
        self.image = placeHolder
        let aRequest = URLRequest(url: anURL, cachePolicy: .returnCacheDataElseLoad, timeoutInterval: 10)
        URLSession(configuration: .default).dataTask(with: aRequest, completionHandler: { (data, response, error) in
            DispatchQueue.main.async {
                if let anError = error as NSError? {
                    AlertController.presentOkayAlert(error: anError)
                }
                else if let tmpData = data, let anImage = UIImage(data: tmpData) {
                    self.image = anImage
                    self.highlightedImage = self.filledImage(source: anImage, fillColor: UIColor.colorWithHexString("#c0c0c0", alpha: 0.6))
                }
            }
        }).resume()
    }

    func filledImage(source: UIImage, fillColor: UIColor) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(source.size, false, UIScreen.main.scale)

        let context = UIGraphicsGetCurrentContext()
        fillColor.setFill()
        context!.translateBy(x: 0, y: source.size.height)
        context!.scaleBy(x: 1.0, y: -1.0)
        context!.setBlendMode(CGBlendMode.colorBurn)
        let rect = CGRect(x: 0, y: 0, width: source.size.width, height: source.size.height)
        context!.draw(source.cgImage!, in: rect)
        context!.setBlendMode(CGBlendMode.normal)
        context!.addRect(rect)
        context!.drawPath(using: CGPathDrawingMode.fill)
        let coloredImg : UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()

        return coloredImg
    }
}