---
title: Creating virtual devices
framework: corehid
role: article
role_heading: Article
path: corehid/creatingvirtualdevices
---

# Creating virtual devices

Use and interact with a virtual human interface device for testing and development.

## Overview

Overview A virtual human interface device (HID) is a software implementation of a hardware device. The system treats the device as any other external peripheral. HIDVirtualDevice models a virtual device and you communicate with it using HIDDeviceClient. Use a virtual device to transport data back and forth between other apps without the need for a connected device. Define the details of a HIDVirtualDevice by passing a set of HIDVirtualDevice.Properties during creation. You must pass descriptor and vendorID, and specify additional properties using init(descriptor:vendorID:productID:transport:product:manufacturer:modelNumber:versionNumber:serialNumber:uniqueID:locationID:localizationCode:extraProperties:). The following creates a HIDVirtualDevice that acts as a keyboard: // This describes a keyboard device according to the Human Interface Devices standard. let keyboardDescriptor: Data = Data([0x05, 0x01, 0x09, 0x06, 0xA1, 0x01, 0x05, 0x07, 0x19, 0xE0, 0x29, 0xE7, 0x15, 0x00, 0x25, 0x01, 0x75, 0x01, 0x95, 0x08, 0x81, 0x02, 0x95, 0x01, 0x75, 0x08, 0x81, 0x01, 0x05, 0x08, 0x19, 0x01, 0x29, 0x05, 0x95, 0x05, 0x75, 0x01, 0x91, 0x02, 0x95, 0x01, 0x75, 0x03, 0x91, 0x01, 0x05, 0x07, 0x19, 0x00, 0x2A, 0xFF, 0x00, 0x95, 0x05, 0x75, 0x08, 0x15, 0x00, 0x26, 0xFF, 0x00, 0x81, 0x00, 0x05, 0xFF, 0x09, 0x03, 0x75, 0x08, 0x95, 0x01, 0x81, 0x02, 0xC0]) let properties = HIDVirtualDevice.Properties(descriptor: keyboardDescriptor, vendorID: 1)

guard let device = HIDVirtualDevice(properties: properties) else {     return } The virtual device adopts the HIDVirtualDeviceDelegate protocol to process report requests. Clients on the system send set reports and receive get reports to and from this virtual device using dispatchSetReportRequest(type:id:data:timeout:) and dispatchGetReportRequest(type:id:timeout:): final class Delegate : HIDVirtualDeviceDelegate {     // A handler for system requests to send data to the device.     func hidVirtualDevice(_ device: HIDVirtualDevice, receivedSetReportRequestOfType type: HIDReportType, id: HIDReportID?, data: Data) throws {         print("Device received a set report request for report type:\(type) id:\(String(describing: id)) with data:[\(data.map { String(format: "%02x", $0) }.joined(separator: " "))]")     }

// A handler for system requests to query data from the device.     func hidVirtualDevice(_ device: HIDVirtualDevice, receivedGetReportRequestOfType type: HIDReportType, id: HIDReportID?, maxSize: size_t) throws -> Data {         print("Device received a get report request for report type:\(type) id:\(String(describing: id))")         assert(maxSize >= 4)         return (Data([1, 2, 3, 4]))     } }

await device.activate(delegate: Delegate()) The virtual device can also dispatch input reports to clients. This is similar to a keyboard dispatching data when a key is pressed. // Send input data to the system to indicate device activity. try await device.dispatchInputReport(data: Data([5, 6, 7, 8]), timestamp: SuspendingClock.now)

## See Also

### Simulation

- [HIDVirtualDevice](corehid/hidvirtualdevice.md)
- [HIDVirtualDeviceDelegate](corehid/hidvirtualdevicedelegate.md)
- [HIDVirtualDevice.Properties](corehid/hidvirtualdevice/properties.md)