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# fetchInstalledExtensions(completionHandler:)

Asynchronously retrieves an list of installed file system modules.

```
func fetchInstalledExtensions(completionHandler: @escaping @Sendable ([FSModuleIdentity]?, (any Error)?) -> Void)
```

## Parameters

`completionHandler`

A block or closure that executes when FSKit finishes its fetch process. If the fetch succeeds, the first parameter contains an array of [`FSModuleIdentity`](/documentation/FSKit/FSModuleIdentity) instances that identify installed modules. If the fetch fails, the second parameter contains an error detailing the failure.

## Discussion

In Swift, you can either call this method and pass a completion handler closure, or get the value of the `installedExtensions` property with the `async` keyword.

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