MetricKit

The MetricKit integration subscribes to MXHangDiagnostic, MXDiskWriteExceptionDiagnostic, and MXCPUExceptionDiagnostic, which it converts to Sentry events.

This feature is available on React Native SDK version 8.22.0 and up. The SDK supports it on iOS 15 and up and macOS 12 and up, because in these versions MetricKit delivers diagnostic reports immediately, which allows the SDK to apply current data from the scope. It isn't available on Android or tvOS.

Enable this feature by setting the enableMetricKit option to true:

import * as Sentry from "@sentry/react-native";

Sentry.init({
  dsn: "___PUBLIC_DSN___",
  enableMetricKit: true,
});

import * as Sentry from "@sentry/react-native";

Sentry.init({
  dsn: "___PUBLIC_DSN___",
  enableMetricKit: true,
});

You can identify MetricKit events by looking at the mx_hang_diagnostic, mx_cpu_exception, and mx_disk_write_exception mechanism.type.

MetricKit Hangs and App Hangs

MetricKit hang diagnostics are reported by the operating system and are separate from the app hangs the SDK detects itself with App Hang Tracking. Both features can be enabled at the same time, but a single unresponsive period may then be reported twice, once from each source.

If you only want the SDK's own detection, leave enableMetricKit disabled. If you want to rely on MetricKit alone, set enableAppHangTracking to false.

Limitations

The SDK has no control over the stack traces provided by MetricKit. Some only offer a couple of frames. If these aren't useful to you, you can drop them in beforeSend.

To read more about how the underlying integration works, check out the sentry-cocoa documentation.