# SnackBar with action no longer auto-dismisses

> SnackBars with an action button now default to not auto-dismissing unless manually dismissed by the user.




:::important
These breaking change docs are accurate, as of the release
under which they are published. Over time, the
workarounds described here might become inaccurate.
We don't, in general, keep these breaking change docs up
to date as of each release.

这些破坏性改动文档的准确性仅限于其发布时对应的版本。
随着时间的推移，文档中描述的方案可能会逐渐失效。
通常情况下，我们不会在每次发布新版本时都对这些文档进行同步更新。

The [breaking change index file](/release/breaking-changes)
lists the docs created for each release.

[破坏性改动列表](/release/breaking-changes) 
列出了每个版本的文档。

:::


## Summary

The default behavior of a [`SnackBar`][] with an action has changed.
Previously, a `SnackBar` with an action wouldn't
auto-dismiss if talkback was enabled.
Now, all `SnackBar` widgets with an action default to
a non-dismissible state until the user interacts with the action button.

## Context

A `SnackBar` with an action button is now treated as
a more persistent notification that requires user interaction.
This change improves accessibility and user experience by ensuring that
critical notifications remain on the screen until they are acknowledged.

## Description of change

This change aligns with the Material 3 design specification for
the `SnackBar` component:

* Old behavior: A `SnackBar` with an action button would auto-dismiss after a
  duration unless talkback was enabled.
* New behavior: A `SnackBar` with an action button won't auto-dismiss;
  it remains on screen until dismissed by the user.

To override this behavior, an optional `persist` property has
been added to `SnackBar`.
When `persist` is `true`, the `SnackBar` won't auto-dismiss and
remains on screen until manually dismissed by the user.
When `false`, the `SnackBar` auto-dismisses after its standard duration,
regardless of the presence of an action.
When `null`, the `SnackBar` follows the default behavior,
which won't auto-dismiss if an action is present.

## Migration guide

To restore the old auto-dismiss behavior for a SnackBar with an action, set
`persist` to `false`.

Code before migration:

```dart
ScaffoldMessenger.of(context).showSnackBar(
  SnackBar(
    content: const Text('This is a snackbar with an action.'),
    action: SnackBarAction(
      label: 'Action',
      onPressed: () {
        // Perform some action
      },
    ),
  ),
);
```

Code after migration:

```dart highlightLines=4
ScaffoldMessenger.of(context).showSnackBar(
  SnackBar(
    content: const Text('This is a snackbar with an action.'),
    persist: false, // Add this line to restore auto-dismiss behavior
    action: SnackBarAction(
      label: 'Action',
      onPressed: () {
        // Perform some action
      },
    ),
  ),
);
```

## Timeline

Landed in version: 3.37.0-0.0.pre
In stable release: 3.38

## References

API documentation:

* [`SnackBar`][]

Relevant PRs:

* [SnackBar with action no longer auto-dismisses][]

[`SnackBar`]: https://api.flutter-io.cn/flutter/material/SnackBar-class.html

[SnackBar with action no longer auto-dismisses]: https://github.com/flutter/flutter/pull/173084