Swift - Problems with corner radius and drop shadow

The following Swift 5 / iOS 12 code shows how to set a subclass of UIButton that allows to create instances with rounded corners and shadow around it:

import UIKit

final class CustomButton: UIButton {

    private var shadowLayer: CAShapeLayer!

    override func layoutSubviews() {
        super.layoutSubviews()

        if shadowLayer == nil {
            shadowLayer = CAShapeLayer()
            shadowLayer.path = UIBezierPath(roundedRect: bounds, cornerRadius: 12).cgPath
            shadowLayer.fillColor = UIColor.white.cgColor

            shadowLayer.shadowColor = UIColor.darkGray.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)
            //layer.insertSublayer(shadowLayer, below: nil) // also works
        }        
    }

}

According to your needs, you may add a UIButton in your Storyboard and set its class to CustomButton or you may create an instance of CustomButton programmatically. The following UIViewController implementation shows how to create and use a CustomButton instance programmatically:

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = CustomButton(type: .system)
        button.setTitle("Button", for: .normal)
        view.addSubview(button)

        button.translatesAutoresizingMaskIntoConstraints = false
        let horizontalConstraint = button.centerXAnchor.constraint(equalTo: view.centerXAnchor)
        let verticalConstraint = button.centerYAnchor.constraint(equalTo: view.centerYAnchor)        
        let widthConstraint = button.widthAnchor.constraint(equalToConstant: 100)
        let heightConstraint = button.heightAnchor.constraint(equalToConstant: 100)
        NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])
    }

}

The previous code produces the image below in the iPhone simulator:

https://i.stack.imgur.com/jWkAf.png

---

My custom button with some shadow and rounded corners, I use it directly within the Storyboard with no need to touch it programmatically.

Swift 4

class RoundedButtonWithShadow: UIButton {
    override func awakeFromNib() {
        super.awakeFromNib()
        self.layer.masksToBounds = false
        self.layer.cornerRadius = self.frame.height/2
        self.layer.shadowColor = UIColor.black.cgColor
        self.layer.shadowPath = UIBezierPath(roundedRect: self.bounds, cornerRadius: self.layer.cornerRadius).cgPath
        self.layer.shadowOffset = CGSize(width: 0.0, height: 3.0)
        self.layer.shadowOpacity = 0.5
        self.layer.shadowRadius = 1.0
    }
}

https://i.stack.imgur.com/bubPM.png

---

To expand on Imanou's post, it's possible to programmatically add the shadow layer in the custom button class

@IBDesignable class CustomButton: UIButton {
    var shadowAdded: Bool = false

    @IBInspectable var cornerRadius: CGFloat = 0 {
        didSet {
            layer.cornerRadius = cornerRadius
            layer.masksToBounds = cornerRadius > 0
        }
    }

    override func drawRect(rect: CGRect) {
        super.drawRect(rect)

        if shadowAdded { return }
        shadowAdded = true

        let shadowLayer = UIView(frame: self.frame)
        shadowLayer.backgroundColor = UIColor.clearColor()
        shadowLayer.layer.shadowColor = UIColor.darkGrayColor().CGColor
        shadowLayer.layer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: self.cornerRadius).CGPath
        shadowLayer.layer.shadowOffset = CGSize(width: 1.0, height: 1.0)
        shadowLayer.layer.shadowOpacity = 0.5
        shadowLayer.layer.shadowRadius = 1
        shadowLayer.layer.masksToBounds = true
        shadowLayer.clipsToBounds = false

        self.superview?.addSubview(shadowLayer)
        self.superview?.bringSubviewToFront(self)
    }
}

---

An alternative way to get more usable and consistent button.

Swift 2:

func getImageWithColor(color: UIColor, size: CGSize, cornerRadius:CGFloat) -> UIImage {
    let rect = CGRectMake(0, 0, size.width, size.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 1)
    UIBezierPath(
        roundedRect: rect,
        cornerRadius: cornerRadius
        ).addClip()
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image
}

let button = UIButton(type: .Custom)
button.frame = CGRectMake(20, 20, 200, 50)
button.setTitle("My Button", forState: UIControlState.Normal)
button.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)
self.addSubview(button)

let image = getImageWithColor(UIColor.whiteColor(), size: button.frame.size, cornerRadius: 5)
button.setBackgroundImage(image, forState: UIControlState.Normal)

button.layer.shadowRadius = 5
button.layer.shadowColor = UIColor.blackColor().CGColor
button.layer.shadowOpacity = 0.5
button.layer.shadowOffset = CGSizeMake(0, 1)
button.layer.masksToBounds = false

Swift 3:

func getImageWithColor(_ color: UIColor, size: CGSize, cornerRadius:CGFloat) -> UIImage? {
    let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    color.setFill()
    UIBezierPath(roundedRect: rect, cornerRadius: cornerRadius).addClip()
    color.setFill()
    UIRectFill(rect)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return image
}

let button = UIButton(type: .custom)
button.frame = CGRect(x:20, y:20, width:200, height:50)
button.setTitle("My Button", for: .normal)
button.setTitleColor(UIColor.black, for: .normal)
self.addSubview(button)

if let image = getImageWithColor(UIColor.white, size: button.frame.size, cornerRadius: 5) {
    button.setBackgroundImage(image, for: .normal)
}

button.layer.shadowRadius = 5
button.layer.shadowColor = UIColor.black.cgColor
button.layer.shadowOpacity = 0.5
button.layer.shadowOffset = CGSize(width:0, height:1)
button.layer.masksToBounds = false

---

Swift 5 & No need of "UIBezierPath"

    view.layer.cornerRadius = 15
    view.clipsToBounds = true
    view.layer.masksToBounds = false
    view.layer.shadowRadius = 7
    view.layer.shadowOpacity = 0.6
    view.layer.shadowOffset = CGSize(width: 0, height: 5)
    view.layer.shadowColor = UIColor.red.cgColor

---

Refactored this to support any view. Subclass your view from this and it should have rounded corners. If you add something like a UIVisualEffectView as a subview to this view you likely need to use the same rounded corners on that UIVisualEffectView or it won't have rounded corners.

https://i.stack.imgur.com/ztnb4.png

/// Inspiration: https://stackoverflow.com/a/25475536/129202
class ViewWithRoundedcornersAndShadow: UIView {
    private var theShadowLayer: CAShapeLayer?

    override func layoutSubviews() {
        super.layoutSubviews()

        if self.theShadowLayer == nil {
            let rounding = CGFloat.init(22.0)

            let shadowLayer = CAShapeLayer.init()
            self.theShadowLayer = shadowLayer
            shadowLayer.path = UIBezierPath.init(roundedRect: bounds, cornerRadius: rounding).cgPath
            shadowLayer.fillColor = UIColor.clear.cgColor

            shadowLayer.shadowPath = shadowLayer.path
            shadowLayer.shadowColor = UIColor.black.cgColor
            shadowLayer.shadowRadius = CGFloat.init(3.0)
            shadowLayer.shadowOpacity = Float.init(0.2)
            shadowLayer.shadowOffset = CGSize.init(width: 0.0, height: 4.0)

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

---

Corner Radius with Shadow

Short and simple way !!!!!

extension CALayer {
    func applyCornerRadiusShadow(
        color: UIColor = .black,
        alpha: Float = 0.5,
        x: CGFloat = 0,
        y: CGFloat = 2,
        blur: CGFloat = 4,
        spread: CGFloat = 0,
        cornerRadiusValue: CGFloat = 0)
    {
        cornerRadius = cornerRadiusValue
        shadowColor = color.cgColor
        shadowOpacity = alpha
        shadowOffset = CGSize(width: x, height: y)
        shadowRadius = blur / 2.0
        if spread == 0 {
            shadowPath = nil
        } else {
            let dx = -spread
            let rect = bounds.insetBy(dx: dx, dy: dx)
            shadowPath = UIBezierPath(rect: rect).cgPath
        }
    }

Use of code

btn.layer.applyCornerRadiusShadow(color: .black, 
                            alpha: 0.38, 
                            x: 0, y: 3, 
                            blur: 10, 
                            spread: 0, 
                            cornerRadiusValue: 24)

No need maskToBound

Please verify clipsToBounds is false.

OUTPUT

https://i.stack.imgur.com/uy1Tx.png

---

To improve PiterPan's answer and show a real shadow (not just a background with no blur) with a circular button in Swift 3:

override func viewDidLoad() {
    super.viewDidLoad()
    myButton.layer.masksToBounds = false
    myButton.layer.cornerRadius = myButton.frame.height/2
    myButton.clipsToBounds = true
}

override func viewDidLayoutSubviews() {
    addShadowForRoundedButton(view: self.view, button: myButton, opacity: 0.5)
}

func addShadowForRoundedButton(view: UIView, button: UIButton, opacity: Float = 1) {
    let shadowView = UIView()
    shadowView.backgroundColor = UIColor.black
    shadowView.layer.opacity = opacity
    shadowView.layer.shadowRadius = 5
    shadowView.layer.shadowOpacity = 0.35
    shadowView.layer.shadowOffset = CGSize(width: 0, height: 0)
    shadowView.layer.cornerRadius = button.bounds.size.width / 2
    shadowView.frame = CGRect(origin: CGPoint(x: button.frame.origin.x, y: button.frame.origin.y), size: CGSize(width: button.bounds.width, height: button.bounds.height))
    self.view.addSubview(shadowView)
    view.bringSubview(toFront: button)
}

---

Exact solution for 2020 syntax

import UIKit
class ColorAndShadowButton: UIButton {
    override init(frame: CGRect) { super.init(frame: frame), common() }
    required init?(coder aDecoder: NSCoder) { super.init(coder: aDecoder), common() }
    private func common() {
        // UIButton is tricky: you MUST set the clear bg in bringup;  NOT in layout
        backgroundColor = .clear
        clipsToBounds = false
        self.layer.insertSublayer(colorAndShadow, below: layer)
    }
    
   lazy var colorAndShadow: CAShapeLayer = {
        let s = CAShapeLayer()
        // set your button color HERE (NOT on storyboard)
        s.fillColor = UIColor.black.cgColor
        // now set your shadow color/values
        s.shadowColor = UIColor.red.cgColor
        s.shadowOffset = CGSize(width: 0, height: 10)
        s.shadowOpacity = 1
        s.shadowRadius = 10
        // now add the shadow
        layer.insertSublayer(s, at: 0)
        return s
    }()
    
    override func layoutSubviews() {
        super.layoutSubviews()
        // you MUST layout these two EVERY layout cycle:
        colorAndShadow.frame = bounds
        colorAndShadow.path = UIBezierPath(roundedRect: bounds, cornerRadius: 12).cgPath
    }
}

Note that the very old top answer here is correct but has a critical error

Note that UIButton is unfortunately quite different from UIView in iOS.

Due to a strange behavior in iOS, you must set the background color (which of course must be clear in this case) in initialization, not in layout. You could just set it clear in storyboard (but you usually click it to be some solid color simply so you can see it when working in storyboard.)

In general combos of shadows/rounding are a real pain in iOS. Similar solutions:

https://stackoverflow.com/a/57465440/294884 - image + rounded + shadows
https://stackoverflow.com/a/41553784/294884 - two-corner problem
https://stackoverflow.com/a/59092828/294884 - "shadows + hole" or "glowbox" problem
https://stackoverflow.com/a/57400842/294884 - the "border AND gap" problem
https://stackoverflow.com/a/57514286/294884 - basic "adding" beziers

---

Extension to drop shadow and corner radius

extension UIView {

func dropShadow(color: UIColor, opacity: Float = 0.5, offSet: CGSize, shadowRadius: CGFloat = 1, scale: Bool = true, cornerRadius: CGFloat) {
    let shadowLayer = CAShapeLayer()
    shadowLayer.path = UIBezierPath(roundedRect: bounds, cornerRadius: cornerRadius).cgPath
    shadowLayer.fillColor = UIColor.white.cgColor
    shadowLayer.shadowColor = color.cgColor
    shadowLayer.shadowPath = shadowLayer.path
    shadowLayer.shadowOffset = offSet
    shadowLayer.shadowOpacity = opacity
    shadowLayer.shadowRadius = shadowRadius
    layer.insertSublayer(shadowLayer, at: 0)
}

}

---

Here is the solution that will work!

extension UIView {

    func applyShadowWithCornerRadius(color:UIColor, opacity:Float, radius: CGFloat, edge:AIEdge, shadowSpace:CGFloat)    {

        var sizeOffset:CGSize = CGSize.zero
        switch edge {
        case .Top:
            sizeOffset = CGSize(width: 0, height: -shadowSpace)
        case .Left:
            sizeOffset = CGSize(width: -shadowSpace, height: 0)
        case .Bottom:
            sizeOffset = CGSize(width: 0, height: shadowSpace)
        case .Right:
            sizeOffset = CGSize(width: shadowSpace, height: 0)


        case .Top_Left:
            sizeOffset = CGSize(width: -shadowSpace, height: -shadowSpace)
        case .Top_Right:
            sizeOffset = CGSize(width: shadowSpace, height: -shadowSpace)
        case .Bottom_Left:
            sizeOffset = CGSize(width: -shadowSpace, height: shadowSpace)
        case .Bottom_Right:
            sizeOffset = CGSize(width: shadowSpace, height: shadowSpace)


        case .All:
            sizeOffset = CGSize(width: 0, height: 0)
        case .None:
            sizeOffset = CGSize.zero
        }

        self.layer.cornerRadius = self.frame.size.height / 2
        self.layer.masksToBounds = true;

        self.layer.shadowColor = color.cgColor
        self.layer.shadowOpacity = opacity
        self.layer.shadowOffset = sizeOffset
        self.layer.shadowRadius = radius
        self.layer.masksToBounds = false

        self.layer.shadowPath = UIBezierPath(roundedRect:self.bounds, cornerRadius:self.layer.cornerRadius).cgPath
    }
}

enum AIEdge:Int {
    case
    Top,
    Left,
    Bottom,
    Right,
    Top_Left,
    Top_Right,
    Bottom_Left,
    Bottom_Right,
    All,
    None
}

Finally, to apply shadow with corner radius call as per below:

viewRounded.applyShadowWithCornerRadius(color: .gray, opacity: 1, radius: 15, edge: AIEdge.All, shadowSpace: 15)

Result Image

https://i.stack.imgur.com/vKBqX.png

UPDATE: If you don't see the expected output then try calling the extension method from Main Thread, that will work for sure!

DispatchQueue.main.async {
    viewRounded.applyShadowWithCornerRadius(color: .gray, opacity: 1, radius: 15, edge: AIEdge.All, shadowSpace: 15)
}

---

If somebody need add shadows to rounded buttons in Swift 3.0, here is a good method to do it.

func addShadowForRoundedButton(view: UIView, button: UIButton, shadowColor: UIColor, shadowOffset: CGSize, opacity: Float = 1) {
    let shadowView = UIView()
    shadowView.backgroundColor = shadowColor
    shadowView.layer.opacity = opacity
    shadowView.layer.cornerRadius = button.bounds.size.width / 2
    shadowView.frame = CGRect(origin: CGPoint(x: button.frame.origin.x + shadowOffset.width, y: button.frame.origin.y + shadowOffset.height), size: CGSize(width: button.bouds.width, height: button.bounds.height))
    self.view.addSubview(shadowView)
    view.bringSubview(toFront: button)
}

Use this method in func viewDidLayoutSubviews() as bellow:

override func viewDidLayoutSubviews() {
    addShadowForRoundedButton(view: self.view, button: button, shadowColor: .black, shadowOffset: CGSize(width: 2, height: 2), opacity: 0.5)
}

https://i.stack.imgur.com/hkS6E.png

---

You can create a protocol and conform it to you UIView, UIButton, Cell or whatever you want like that:

protocol RoundedShadowable: class {
    var shadowLayer: CAShapeLayer? { get set }
    var layer: CALayer { get }
    var bounds: CGRect { get }
}
​
extension RoundedShadowable {
    func applyShadowOnce(withCornerRadius cornerRadius: CGFloat, andFillColor fillColor: UIColor) {
        if self.shadowLayer == nil {
            let 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: 0.0, height: 2.0)
            shadowLayer.shadowOpacity = 0.2
            shadowLayer.shadowRadius = 3
            self.layer.insertSublayer(shadowLayer, at: 0)
            self.shadowLayer = shadowLayer
        }
    }
}
​
class RoundShadowView: UIView, RoundedShadowable {

    var shadowLayer: CAShapeLayer?
    private let cornerRadius: CGFloat
    private let fillColor: UIColor

    init(cornerRadius: CGFloat, fillColor: UIColor) {
        self.cornerRadius = cornerRadius
        self.fillColor = fillColor
        super.init(frame: .zero)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        self.applyShadowOnce(withCornerRadius: self.cornerRadius, andFillColor: self.fillColor)
    }
}
​
class RoundShadowButton: UIButton, RoundedShadowable {

    var shadowLayer: CAShapeLayer?
    private let cornerRadius: CGFloat
    private let fillColor: UIColor

    init(cornerRadius: CGFloat, fillColor: UIColor) {
        self.cornerRadius = cornerRadius
        self.fillColor = fillColor
        super.init(frame: .zero)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        self.applyShadowOnce(withCornerRadius: self.cornerRadius, andFillColor: self.fillColor)
    }
}

---