如何在单元格中的UIImageView上添加蒙版-Swift

Question

I've a tableView and I'm trying to add black mask on each image in the cell not on the whole cell just on the image. But I have two issues;

-It is masking the half cell from the left to the middle and each I scroll it is becoming darker. So please where would be my issue?

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("cell") as! PlacesTableViewCell

        cell.backgroundImage.sd_setImageWithURL(NSURL(string: place.Image), placeholderImage: nil, options: .HighPriority)
}

class PlacesTableViewCell: UITableViewCell {
    override func layoutSubviews() {
    super.layoutSubviews()
    maskArrangement()
}

func maskArrangement(){
    var maskLayer = CALayer()
    maskLayer.frame = CGRectMake(0, 0, backgroundImage.frame.size.width, backgroundImage.frame.size.height)
    maskLayer.backgroundColor = UIColor(white: 0.0, alpha: 0.5).CGColor
    //backgroundImage.layer.mask = maskLayer
    backgroundImage.layer.addSublayer(maskLayer)
    }
}

Answer 1

Every time cell is dequeued you are adding new sublayer to your backgroundImage. In this way it is getting darker when you scroll (when you dequeued your cells). I think you can add to your PlacesTableViewCell class at awakeFromNib method if it has a .xib file.

Meanwhile your image's frame should be half of the cell. Use autolayout to fix it's frame (for instance, set width and height constraints) in your PLacesTableViewCell class.

In @Shripada 's way:

class PlacesTableViewCell: UITableViewCell {
    var maskLayer : CALayer
    override func layoutSubviews() {
    super.layoutSubviews()
    maskArrangement()
}

    func maskArrangement(){
        if maskLayer == nil {
            maskLayer.frame = CGRectMake(0, 0, backgroundImage.frame.size.width, backgroundImage.frame.size.height)
            maskLayer.backgroundColor = UIColor(white: 0.0, alpha: 0.5).CGColor
            //backgroundImage.layer.mask = maskLayer
            backgroundImage.layer.addSublayer(maskLayer)
        }
    }
}

I haven't tried this code. But your solution can be like that.