I'm curious about how to use Xcode Instruments for a React Native iOS app. Could you provide some guidance?

[swkhang]

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I am experiencing issues while profiling an iOS app developed with React Native.

I attempted to verify if the memory leak examples purportedly related to React Native would be detected by the Xcode Instruments Leaks template. However, in all cases, no memory leaks were detected.

Is there anyone who can provide a practical example of a memory leak in React Native that can be detected using the Xcode Instruments Leaks template?

Or is there an additional step required to apply the Instruments tool to React Native code?

Currently, I am using React Native 0.74.2 and Xcode 15.2, and my test involved simply running Instruments in Xcode, opening the app with the Leaks template, and conducting the test.

Here is the example code:

const MemoryLeakExample = () => {
useEffect(() => {
const intervalId = setInterval(() => {
console.log('interval is running');
}, 1000);
return () => {
console.log('leak');
};
}, []);
return (

MemoryLeak Example

);
};

[richardfariax]

Instruments + RN can be confusing because a lot of your JS leaks show up under different stacks, and small leaks won't always trigger the Leaks instrument immediately.

What I'd do:

1. Profile a Release build on a real device (not Debug). Debug RN builds have way more noise.

2. In Xcode: Product → Profile → pick Leaks or Allocations. Let the app run, exercise the screen you suspect, background/foreground a few times.

3. For JS-side issues, also try React Native Performance monitor + Flipper/hermes sampling. Pure native Leaks won't always catch JS closures holding native refs.

4. Reproducible native leak example — mount/unmount a screen in a loop that creates Animated values or subscriptions without cleanup. But honestly, most "RN memory leaks" I've seen were:

   • listeners not removed (AppState, NetInfo, navigation listeners)
   • useEffect missing cleanup
   • images/cache not cleared

5. Make sure you're on Hermes and RN 0.74+ has better profiling story than older versions.

If Leaks shows nothing but memory climbs in Allocations, that's still useful — share a screenshot of the call tree and what screen you repeated.