NEW BOOK: Code got you started. This gets you paid. >>

How to force a UIView to redraw: setNeedsDisplay()

Swift version: 5.10

Paul Hudson    @twostraws   

All views and subclasses are rendered using the drawRect() method, but you should never call that method directly yourself. Instead, it gets called by the system whenever drawing is required, which allows it to to avoid multiple redraws if drawRect() is called several times in a row.

Instead, if you want a view to redraw immediately, you should call its setNeedsDisplay() method like this:

myButton.setNeedsDisplay()

That will ask UIKit to redraw the button using drawRect(), but only if a redraw is not already queued.

Hacking with Swift is sponsored by Superwall.

SPONSORED Join some of the App Store’s biggest apps—from brands like Mojo and Citizen to thriving indies. Test pricing, run paywall experiments, update locked features, and now, launch web checkout links straight from your app—all without updates. Superwall is your complete growth toolkit.

Try now

Available from iOS 2.0

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 OUR BOOKS
Buy Pro Swift Buy Pro SwiftUI Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Interview Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS 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: 3.6/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.