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# enqueueIORequest(with:transactionList:transactionListCount:firstFrameNumber:options:completionHandler:)

```
func enqueueIORequest(with data: NSMutableData, transactionList: UnsafeMutablePointer<IOUSBHostIsochronousTransaction>, transactionListCount: Int, firstFrameNumber: UInt64, options: IOUSBHostIsochronousTransferOptions = [], completionHandler: (@Sendable (IOReturn, UnsafeMutablePointer<IOUSBHostIsochronousTransaction>) -> Void)? = nil) throws
```

## Discussion

> Important:
> You can call this method from synchronous code using a completion handler, as shown on this page, or you can call it as an asynchronous method that has the following declaration:
> 
> ```swift
> func enqueueIORequest(with data: NSMutableData, transactionList: UnsafeMutablePointer<IOUSBHostIsochronousTransaction>, transactionListCount: Int, firstFrameNumber: UInt64, options: IOUSBHostIsochronousTransferOptions = []) async throws -> (IOReturn, UnsafeMutablePointer<IOUSBHostIsochronousTransaction>)
> ```
> 
> For information about concurrency and asynchronous code in Swift, see <doc://com.apple.documentation/documentation/Swift/calling-objective-c-apis-asynchronously>.

---

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