add Shadow on UIView using swift 3

Question

prior swift 3 i was adding shadow in my UIView like this :

//toolbar is an UIToolbar (UIView)
toolbar.layer.masksToBounds = false
toolbar.layer.shadowOffset = CGSize(width: -1, height: 1)
toolbar.layer.shadowRadius = 1
toolbar.layer.shadowOpacity = 0.5

but the above code is not working in swift 3 , instead of shadow my whole View's color is turned to ugly gray

anyone knows how can we add shadow in swift 3 ?

Answer 1

Very simple and few lines of code:

let viewShadow = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
viewShadow.center = self.view.center
viewShadow.backgroundColor = UIColor.yellow
viewShadow.layer.shadowColor = UIColor.red.cgColor
viewShadow.layer.shadowOpacity = 1
viewShadow.layer.shadowOffset = CGSize.zero
viewShadow.layer.shadowRadius = 5
self.view.addSubview(viewShadow)

Look like :

Answer 2

loginView.layer.shadowOpacity = 1.0

Answer 3

If you need rounded shadow. Works for swift 4.2

extension UIView {

        func dropShadow() {

            var shadowLayer: CAShapeLayer!
            let cornerRadius: CGFloat = 16.0
            let fillColor: UIColor = .white

            if shadowLayer == nil {
                shadowLayer = CAShapeLayer()

                shadowLayer.path = UIBezierPath(roundedRect: bounds, cornerRadius: cornerRadius).cgPath
                shadowLayer.fillColor = fillColor.cgColor

                shadowLayer.shadowColor = UIColor.black.cgColor
                shadowLayer.shadowPath = shadowLayer.path
                shadowLayer.shadowOffset = CGSize(width: -2.0, height: 2.0)
                shadowLayer.shadowOpacity = 0.8
                shadowLayer.shadowRadius = 2

                layer.insertSublayer(shadowLayer, at: 0)
            }
        }
    }

Swift 4 rounded UIView with shadow

Answer 4

CODE SNIPPET:

extension UIView {

  // OUTPUT 1
  func dropShadow(scale: Bool = true) {
    layer.masksToBounds = false
    layer.shadowColor = UIColor.black.cgColor
    layer.shadowOpacity = 0.5
    layer.shadowOffset = CGSize(width: -1, height: 1)
    layer.shadowRadius = 1

    layer.shadowPath = UIBezierPath(rect: bounds).cgPath
    layer.shouldRasterize = true
    layer.rasterizationScale = scale ? UIScreen.main.scale : 1
  }

  // OUTPUT 2
  func dropShadow(color: UIColor, opacity: Float = 0.5, offSet: CGSize, radius: CGFloat = 1, scale: Bool = true) {
    layer.masksToBounds = false
    layer.shadowColor = color.cgColor
    layer.shadowOpacity = opacity
    layer.shadowOffset = offSet
    layer.shadowRadius = radius

    layer.shadowPath = UIBezierPath(rect: self.bounds).cgPath
    layer.shouldRasterize = true
    layer.rasterizationScale = scale ? UIScreen.main.scale : 1
  }
}

NOTE: If you don't pass any parameter to that function, then the scale argument will be true by default. You can define a default value for any parameter in a function by assigning a value to the parameter after that parameter’s type. If a default value is defined, you can omit that parameter when calling the function.

OUTPUT 1:

shadowView.dropShadow()

OUTPUT 2:

shadowView.dropShadow(color: .red, opacity: 1, offSet: CGSize(width: -1, height: 1), radius: 3, scale: true)

layer.shouldRasterize = true will make the shadow static and cause a shadow for the initial state of the UIView. So I would recommend not to use layer.shouldRasterize = true in dynamic layouts like view inside a UITableViewCell.

Answer 5

If you want to use it as a IBInspectable property for your views you can add this extension

import UIKit

extension UIView {

    private static var _addShadow:Bool = false

    @IBInspectable var addShadow:Bool {
        get {
            return UIView._addShadow
        }
        set(newValue) {
            if(newValue == true){
                layer.masksToBounds = false
                layer.shadowColor = UIColor.black.cgColor
                layer.shadowOpacity = 0.075
                layer.shadowOffset = CGSize(width: 0, height: -3)
                layer.shadowRadius = 1

                layer.shadowPath = UIBezierPath(rect: bounds).cgPath
                layer.shouldRasterize = true
                layer.rasterizationScale =  UIScreen.main.scale
            }
        }
    }

}

Answer 6

I would like to add one more line with selected answer! When we rasterizing the layer, It needs to be set to 2.0 for retina displays. Otherwise label text or images on that view will be blurry. So we need to add rasterizationScale also.

  extension UIView {

    func dropShadow() {

        self.layer.masksToBounds = false
        self.layer.shadowColor = UIColor.black.cgColor
        self.layer.shadowOpacity = 0.5
        self.layer.shadowOffset = CGSize(width: -1, height: 1)
        self.layer.shadowRadius = 1

        self.layer.shadowPath = UIBezierPath(rect: self.bounds).cgPath
        self.layer.shouldRasterize = true

        self.layer.rasterizationScale = UIScreen.main.scale

    }
}