Add shadowPath to UITableView subclass - swift

Question

I want to create a shadow on a subview on my UITableView:
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
mainBackground = UIView()
super.init(style: style, reuseIdentifier: reuseIdentifier)
backgroundColor = .clear
mainBackground.backgroundColor = .red
mainBackground.translatesAutoresizingMaskIntoConstraints = false
mainBackground.layer.cornerRadius = 15
mainBackground.layer.masksToBounds = true
contentView.addSubview(mainBackground)
setupConstraints()
}
func setupConstraints() {
NSLayoutConstraint.activate([
mainBackground.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 5),
mainBackground.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -5),
mainBackground.leadingAnchor.constraint(equalTo: contentView.leadingAnchor),
mainBackground.widthAnchor.constraint(equalTo: contentView.widthAnchor, multiplier: 0.5)
])
}
I'm placing my shadow code in layoutSubviews, where I also use UIEdgeInsets to make my subview smaller:
override func layoutSubviews() {
super.layoutSubviews()
let margins = UIEdgeInsets(top: 5, left: 8, bottom: 5, right: 8)
contentView.frame = contentView.frame.inset(by: margins)
contentView.layer.cornerRadius = 8
setupShadow()
}
public func setupShadow() {
self.layer.shadowOffset = CGSize(width: 0, height: 3)
self.layer.shadowRadius = 3
self.layer.shadowOpacity = 1.0
self.layer.shadowColor = UIColor.black.cgColor
self.layer.shadowPath = UIBezierPath(rect: self.mainBackground.frame).cgPath
self.clipsToBounds = true
}
Without the shadowPath this seems to work, but with it I don't get a shadow at all. I want to use a shadowPath to make the drawing of the shadow efficient. How do I add the shadowPath here?

Answer 1

I'm sorry I don't quite understand what kind of result do you expect to achieve.
I don't think it's possible to get any kind of "shadow" for a UITableViewCell because usually shadows are outside/around the view, but table view cells stay next to each other, without any gap in between. So any shadow of the first cell will be overlapped by the second cell.
self.layer.shadowPath = UIBezierPath(rect: self.mainBackground.frame).cgPath
here you add a shadow to the cell, but the shadow is overlapped by mainBackgroundView so the shadow is invisible
try that:
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
mainBackground.backgroundColor = .red
mainBackground.translatesAutoresizingMaskIntoConstraints = false
mainBackground.layer.cornerRadius = 15
mainBackground.layer.shadowOffset = CGSize(width: 0, height: 3)
mainBackground.layer.shadowRadius = 3
mainBackground.layer.shadowOpacity = 1.0
mainBackground.layer.shadowColor = UIColor.black.cgColor
contentView.addSubview(mainBackground)
}
override func layoutSubviews() {
super.layoutSubviews()
mainBackground.frame = contentView.bounds.insetBy(dx: 20, dy: 20)
mainBackground.layer.shadowPath = UIBezierPath(rect: self.mainBackground.bounds).cgPath
}
and increase the height of your cells to ~100pt
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
100
}
and you will be able to play with a shadow applied to mainBackgroundView

Answer 2

Try this,
var setupShadowDone: Bool = false
public func setupShadow() {
if setupShadowDone { return }
print("Setup shadow!")
self.layer.cornerRadius = 8
self.layer.shadowOffset = CGSize(width: 0, height: 3)
self.layer.shadowRadius = 3
self.layer.shadowOpacity = 0.3
self.layer.shadowColor = UIColor.black.cgColor
self.layer.shadowPath = UIBezierPath(roundedRect: self.bounds,
byRoundingCorners: .allCorners, cornerRadii: CGSize(width: 8, height:
8)).cgPath
self.layer.shouldRasterize = true
self.layer.rasterizationScale = UIScreen.main.scale
setupShadowDone = true
}
override func layoutSubviews() {
super.layoutSubviews()
print("Layout subviews!")
setupShadow()
}