NEW: Join my free 100 Days of SwiftUI challenge today! >>

How to set baselines for your performance tests

Swift version: 5.1

Paul Hudson    @twostraws   

All performance tests in Xcode can have baselines attached to them, which are stored results that you consider representative of your app’s performance as things stand. The baseline is useful because it gives Xcode a measuring point for all other changes you make: if you accidentally change your code so that it runs slower, Xcode will consider your performance test to be a failure.

To set a baseline for a performance test, first make sure it has been run at least once. You should see a gray bar next to the test saying “No baseline average for time”, but if you click the gray diamond to the left of your test a balloon appears offering more information.

To set a baseline, click the Set Baseline button inside that balloon. You’ll see a “Max STDDEV” field set to 10% by default – that’s how much variance Xcode allows before it considers a test to have failed, but you can change it however you want. Broadly speaking, extremely fast code should have a higher standard deviation allowance than slower code, only because extremely fast code is likely to show more variance due to system conditions.

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

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 Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three 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 Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 3.0/5