Systrace doesn't show JavasScript stuff after upgrade to React Native 0.27.0

Question

I use systrace on on IOS (from the devge-shake dev menu) to track performance issues. It used to display information about which views take time, but after upgrading to 0.27.0 my Systrace profiles no longer display details from parts of JavaScript. I cannot find much documentation or discussion of Systrace, so I am not sure if this is a bug or just a change in its operation.

Any help would be appreciated!

Answer 1

Running javascript for profiling is only possible in DEV mode at this time: check the source code.

• Open the AppDelegate.m file in Xcode.
• Add dev=true request to jsCodeLocation string.

jsCodeLocation = [NSURL URLWithString: @ " http: // localhost: 8081 / index.ios.bundle? platform = ios & dev = true "];