Learn more about what Sentry uses to create a trail of events (breadcrumbs) that happened prior to an issue.

Sentry uses breadcrumbs to create a trail of events that happened prior to an issue. These events are very similar to traditional logs, but can record more rich structured data.

This page provides an overview of manual breadcrumb recording and customization. Learn more about the information that displays on the Issue Details page and how you can filter breadcrumbs to quickly resolve issues in Using Breadcrumbs.

You can manually add breadcrumbs whenever something interesting happens. For example, you might manually record a breadcrumb if the user authenticates or another state change occurs.

Manually record a breadcrumb:

import Sentry

let crumb = Breadcrumb()
crumb.level =
crumb.category = "auth"
crumb.message = "Authenticated user \("
SentrySDK.addBreadcrumb(crumb: crumb)

The Cocoa SDK captures breadcrumbs automatically for:

  • Application lifecycle events (didBecomeActive, didEnterBackground, viewDidAppear)
  • UIControl events (with the exception of UITextField .editingChanged)
  • System events (battery level or state changed, memory warnings, device orientation changed, keyboard did show and did hide, screenshot taken)
  • Outgoing HTTP requests

SDKs allow you to customize breadcrumbs through the beforeBreadcrumb hook.

This hook is passed an already assembled breadcrumb and, in some SDKs, an optional hint. The function can modify the breadcrumb or decide to discard it entirely by returning nil:

import Sentry

SentrySDK.start { options in
    options.beforeBreadcrumb = { crumb in
        return crumb
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