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

How to detect when your size class changes

Swift version: 5.1

Paul Hudson    @twostraws   

All view controllers have a size class, which is a vague description of how much space is available both horizontally and vertically. These sometimes change when the user rotates their device, but can also change on iPad when they split the screen between two apps in various ways.

If your app needs to respond to size class changes, it’s important you implement the traitCollectionDidChange method. There you can check the size class of the current trait collection and respond appropriately. For example:

override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
    if traitCollection.horizontalSizeClass == .compact {
        // load slim view
    } else {
        // load wide view
    }
}

LEARN SWIFTUI FOR FREE I have a massive, free SwiftUI video collection on YouTube teaching you how to build complete apps with SwiftUI – check it out!

Available from iOS 8.0

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.

MASTER SWIFT NOW
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: 4.0/5