How do you debug an issue with a release mode build in iOS?

Question

I am working on an iOS app and I have noticed a bug that is only reproducible when the app is built in release mode. The only way I have found to run a release mode app that

Answer 1

To debug an iOS application in release mode modify the settings: Build Settings -> Deployment -> Deployment Post Processing -> Release -> set value as "NO"

Set 'Deployment Post Processing: Release' value as 'No'

Answer 2

Normally Debug builds have optimisation disabled (-O0) to make debugging easier, whereas Release builds have optimisation enabled (-O3 or -Os), which makes the code run much faster, but also makes debugging harder (but not impossible). You can just go into the build settings in Xcode in the Debug configuration and temporarily turn up the optimisation level - this will keep all the other debug goodies (symbols etc) but hopefully also flush out the Release mode bug. (Don't forget to reset the optimisation level to -O0 in the Debug configuration when you're done!)

Answer 3

1. Go to "Project" command in an Xcode application menu and chose "Edit Scheme"(Shortcut: ⌘< )
2. Select "Run Project name" in left pane
3. In right pane, under "Info" tab change "Build Configuration" to "Release"

Answer 4

You can not run an app in release mode while have having debugging turned on. That is not intended.

When running an app in release mode you have to find a different way to observe the behaviour of your app (e.g. using alerts).

Additionally you will have to trust the distribution profile on your device. Xcode will notify and guide you with an alert message on the first run.

Answer 5

I had to briefly turn on automatic signing in order to accomplish this. You aren't able to build directly on device with an iOS Distribution certificate (you need an iOS Development certificate) and you can't release to the App Store with an iOS Development certificate (you need an iOS Distribution certificate).

My debug mode was configured to use an iOS Development certificate to build directly on device. My release mode was configured to use an iOS Distribution certificate to allow the app to be installed on all devices. In order to run in release mode on device I switched to automatic code signing briefly to test. Once I was done testing, I used git to revert to the previous Xcode configuration.

Not the most elegant way, but it got the job done.