NEW: Nominations are now open for the 2019 Swift Community Awards! >>

How to add a shadow to a UIView

Swift version: 5.1

Paul Hudson    @twostraws   

iOS can dynamically generate shadows for any UIView, and these shadows automatically adjust to fit the shape of the item in question – even following the curves of text inside a UILabel. This functionality is built right in, so all you need to do is configure its properties, and there are four you need to care about:

  • shadowColor sets the color of the shadow, and needs to be a CGColor.
  • shadowOpacity sets how transparent the shadow is, where 0 is invisible and 1 is as strong as possible.
  • shadowOffset sets how far away from the view the shadow should be, to give a 3D offset effect.
  • shadowRadius sets how wide the shadow should be.

Here's a simple example to get you started:

let yourView = UIView()
yourView.layer.shadowColor =
yourView.layer.shadowOpacity = 1
yourView.layer.shadowOffset = .zero
yourView.layer.shadowRadius = 10

Be warned: generating shadows dynamically is expensive, because iOS has to draw the shadow around the exact shape of your view's contents. If you can, set the shadowPath property to a specific value so that iOS doesn't need to calculate transparency dynamically. For example, this creates a shadow path equivalent to the frame of the view:

yourView.layer.shadowPath = UIBezierPath(rect: yourView.bounds).cgPath

Alternatively, ask iOS to cache the rendered shadow so that it doesn't need to be redrawn:

yourView.layer.shouldRasterize = true

If you want to go down the rasterization route, you should make sure iOS caches the shadow at the same drawing scale as the main screen, otherwise it will look pixelated:

yourView.layer.rasterizationScale = UIScreen.main.scale

SAVE 20% ON iOS CONF SG The largest iOS conference in Southeast Asia is back in Singapore for the 5th time in January 2020, now with two days of workshops plus two days of talks on SwiftUI, Combine, GraphQL, and more! Save a massive 20% on your tickets by clicking on this link.

Available from iOS 3.2

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

Buy Testing Swift Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.9/5