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# isMultiThreaded()

Returns whether the application is multithreaded.

```
class func isMultiThreaded() -> Bool
```

## Return Value

<doc://com.apple.documentation/documentation/Swift/true> if the application is multithreaded, otherwise <doc://com.apple.documentation/documentation/Swift/false>.

## Discussion

An application is considered multithreaded if a thread was ever detached from the main thread using either [`detachNewThreadSelector(_:toTarget:with:)`](/documentation/Foundation/Thread/detachNewThreadSelector(_:toTarget:with:)) or [`start()`](/documentation/Foundation/Thread/start()). If you detached a thread in your application using a non-Cocoa API, such as the POSIX or Multiprocessing Services APIs, this method could still return <doc://com.apple.documentation/documentation/Swift/false>. The detached thread does not have to be currently running for the application to be considered multithreaded—this method only indicates whether a single thread has been spawned.

---

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