How to mask UIViews in iOS

Question

I\'ve seen similar questions, but haven\'t found workable answers.

I want to mask a UIView using a grey image (need to convert to alpha scale for masking). The UIVi

Answer 1

For apps targeting iOS 8.0+ this worked well (in this case, using a gradient as the mask) It avoids any need to resize or position the mask.

// Add gradient mask to view
func addGradientMask(targetView: UIView)
{
    let gradientMask = CAGradientLayer()

    gradientMask.frame = targetView.bounds
    gradientMask.colors = [UIColor.blackColor().CGColor, UIColor.clearColor().CGColor]
    gradientMask.locations = [0.8, 1.0]

    let maskView: UIView = UIView()
    maskView.layer.addSublayer(gradientMask)

    targetView.maskView = maskView 
}

In my case, I want to remove the mask once the user starts scrolling. This is done with:

func scrollViewWillBeginDragging(scrollView: UIScrollView) {

    exerDetailsTableView.maskView = nil        
}

where the view is defined as an @IBOutlet:

@IBOutlet weak var exerDetailsTableView: UITableView!

Result: