WWDC Notes

Debugging in Xcode 11

Show Apple's description.
Xcode 11 introduces new features for finding and fixing bugs fast. Discover how to simulate network conditions and thermal states, and how to override your app's runtime environment while debugging. See how the debugging features work with Xcode previews to identify issues before Build & Run. Learn how to work with the View Debugger to troubleshoot your SwiftUI views.

Thermal State Condition

  • can set one of the following: fair, serious, critical.
  • lets us analyze our app behavior in these states.
  • The device does not actually get warmer.
  • Useful if we observe and behave differently when we have different thermal states.
  • We have a new thermal state in the Debug Navigator.
  • To override this setting we must go in the Device and Simulator window, choose a device and then we can set the condition:
  • In the device itself we will see the condition in the background filler around the time (like we see now when we have an active call, also called status bar indicator)
  • To stop the condition we can:
    • quit Xcode
    • disconnect the device
    • Go back in the Device & window
    • Tap on the status bar indicator

Network Link Condition

Updated with new range of options, same as above.

Environment Overrides

You can change things like:

  • Interface appearance
  • Dynamic Type
  • And Accessibility Options

You can use them both while Debugging the simulator or while debugging a SwiftUI live view.

New Run Time Issue Breakpoint

Debugging SwiftUI Live Previews

  • Control+click on the play button to choose to debug a preview, then it behaves like a normal debug session.
  • Do not change the window where the previewed view is, or the debugging session will disappear instantly.

##SwiftUI Runtime Issues

  • Equivalent to auto layout issues or when we try to change our UI from a background thread, they point out issues of our SwiftUI usage.
  • These are shown even when debugging SwiftUI Live Previews, in fact the live preview is a mini-app where we only focus on that view. (Every change builds and runs that view, it’s not really "live")

You can also refresh a SwiftUI preview via shortcut ⌥⌘P.

UI Debugger Enhancements

  • CustomReflectable Protocol
  • Use this protocol in your view to show the data you need while debugging in the UI Debugger Inspector
  • Trait Collections in the UI Debugger
  • Named Assets: For image views, we get image name and other info if it’s a symbol image: The same for colors, now we get the color name displayed .
  • Constraints: the constraints view in UI Debugger also look much better and similar to interface builder:

Missing anything? Corrections? Contributions are welcome 😃

Related

Written by

zntfdr

Federico Zanetello

Federico Zanetello is an iOS Engineer with strong passion for Swift, minimalism, and design. When he’s not busy automating things, he can be found writing at fivestars.blog and/or playing with the latest shiny toys.