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Core Bluetooth Mock

Version number

The Core Bluetooth Mock library was designed to emulate Core Bluetooth objects, providing easy way to test Bluetooth-enabled apps. As the native Bluetooth API is not supported on a simulator, using this library you can run, test and take screenshots of such apps without the need of a physical phone or tablet. You may also start working on the iOS app when your peripheral is still under development.

Core Bluetooth?

The Core Bluetooth framework provides the classes needed for your apps to communicate with Bluetooth-equipped low energy (LE) wireless technology. It requires an iPhone or iPad to work making Bluetooth-enabled apps difficult to test. As the documentation states:

Don’t subclass any of the classes of the Core Bluetooth framework. Overriding these classes isn’t supported and results in undefined behavior.

Core Bluetooth Mock!

The Core Bluetooth Mock library defines number of CBM... classes and constants, that wrap or imitate the corresponding CB... counterparts from Core Bluetooth framework. For example, CBMCentralManager has the same API and behavior as CBCentralManager, etc. On physical iDevices all calls to CBMCentralManager and CBMPeripheral are forwarded to their native equivalents, but on a simulator a mock implementation that you define is used.

How to start

The Core Bluetooth Mock library is available only in Swift, and compatible with iOS 8.0+. For projects running Objective-C we recommend https://github.com/Rightpoint/RZBluetooth library.

Import library from CocoaPods:

pod 'CoreBluetoothMock'

With this complete, you need to choose one of the following approaches:

Using aliases (recommended)

Copy CoreBluetoothTypeAliases.swift file to your project. It will create number of type aliases for all CBM... names and rename them to CB..., so you will not need to perform any changes in your code, except from removing import CoreBluetooth in all your files, as the types are now defined locally.


Replace import CoreBluetooth with import CoreBluetoothMock in your classes.

Replace all instances of CB... with CBM....

Other required changes

The only difference is how the central manager is instantiated. Instead of:

let manager = CBCentralManager(delegate: self, queue: ...)

you need to use the CBCentralManagerFactory:

let manager = CBCentralManagerFactory.initiate(delegate: self, queue: ...)

The last parameter, forceMock, when set to true, allows to run mock implementation also on a physical device.

Defining mock peripherals

When the app using Core Bluetooth Mock library is started on a simulator, or the forceMock parameter is set to true during instantiating a central manager instance, a mock version of central manager will be created. Use the following methods and properties to simulate central manager behavior:


CBMCentralManagerMock.simulateInitialState(_ state: CBMManagerState) - this method should be called before any central manager instance was created. It defines the intial state of the mock central manager. By default, the manager is powered off.

CBMCentralManager.simulatePowerOn() - turns on the mock central manager.

CBMCentralManager.simulatePowerOff() - turns off the mock central manager. All scans and connections will be terminated.

CBMCentralManagerMock.simulatePeripherals(_ peripherals: [CBMPeripheralSpec]) - defines list of mock peripheral. This method should be called once, before any central manager was initialized.

See AppDelegate.swift for reference. In the sample app the mock implementation is used only in UI Tests, which lauch the app with mocking-enabled parameter (see here), but can be easily modified to use it every time it is launched on a simulator or a device.

Peripheral specs

CBMPeripheralSpec.Builder - use the builder to define your mock peripheral. Specify the proximity, whether it is advertising together with advertising data and advertising interval, is it connectable (or already connected when your app starts), by defining its services and their behavior. A ist of such peripheral specifications needs to be set by calling the simulatePeripherals(:) method described above.

CBMPeripheralSpec.simulateConnection() - simulates a situation when another app on the iDevice connects to this peripheral. It will stop advertising (unless advertisingWhenConnected flag was set) and will be available using manager.retrieveConnectedPeripherals(withServices:).

CBMPeripheralSpec.simulateDisconnection(withError:) - simulates a connection error.

CBMPeripheralSpec.simulateReset() - simulates device hard reset. The central will notify delegates 4 seconds (supervision timeout) after the device has been reset.

CBMPeripheralSpec.simulateProximityChange(:) - simulates moving the peripheral close or away from the device.

CBMPeripheralSpec.simulateValueUpdate(:for:) - simulates sending a notification or indication from the device. All subscribed clients will be notified a connection interval later.

See AppDelegate.swift for reference, where 3 mock peripherals are defined: a test blinky device (like in Nordic SDK), an HRM device (GATT behavior not implemented, as the app does not support it), and a Physical Web Beacon, a non-connectable device. The 2 latter will not pop up on in the sample app, as it is scanning with Service UUID filter.


CBMCentralManagerFactory.simulateStateRestoration - this closure will be used when you initiate a central manager with CBMCentralManagerOptionRestoreIdentifierKey option. The map returned will be passed to centralManager(:willRestoreState:) callback in central manager's delegate.

CBMCentralManagerFactory.simulateFeaturesSupport - this closure will be used to emulate Bluetooth features supported by the manager. It is availalbe on iOS 13+.

Sample application: nRF BLINKY

nRF Blinky is an example app targeted towards newcomer BLE developers, and also demonstrating the use of Core Bluetooth Mock library. This application controls an LED on an nRF5DK and receive notifications whenever the button on the kit is pressed and released.

The mock implementation is used in UI tests. See AppDelegate.swift and UITests.swift classes.

Nordic LED and Button Service

Service UUID: 00001523-1212-EFDE-1523-785FEABCD123

A simplified proprietary service by Nordic Semiconductor, containing two characteristics one to control LED3 and Button1:

  • First characteristic controls the LED state (On/Off).

    • UUID: 00001525-1212-EFDE-1523-785FEABCD123
    • Value: 1 => LED On
    • Value: 0 => LED Off
  • Second characteristic notifies central of the button state on change (Pressed/Released).

    • UUID: 00001524-1212-EFDE-1523-785FEABCD123
    • Value: 1 => Button Pressed
    • Value: 0 => Button Released

    For full specification, check out documentation.


  • An iOS device with BLE capabilities, or a simulator (to run the mock)
  • A Development Kit (unless testing mock)
  • The Blinky example firmware to flash on the Development Kit. For your conveninence, we have bundled two firmwares in this project under the Firmwares directory.
  • To get the latest firmwares and check the source code, you may go directly to our Developers website and download the SDK version you need, then you can find the source code and hex files to the blinky demo in the directory /examples/ble_peripheral/ble_app_blinky/
  • More information about the nRFBlinky example firmware can be found in the documentation.

Installation and usage:

  • Prepare your Development kit.

    • Plug in the Development Kit to your computer via USB.
    • Power On the Development Kit.
    • The Development Kit will now appear as a Mass storage device.
    • Drag (or copy/paste) the appropriate HEX file onto that new device.
    • The Development Kit LEDs will flash and it will disconnect and reconnect.
    • The Development Kit is now ready and flashed with the nRFBlinky example firmware.
  • Start Xcode and run build the project against your target iOS Device (Note: BLE is not available in the iOS simulator, so the iOS device is a requirement to test with real hardware).

    • Launch the nRF Blinky app on your iOS device.
    • The app will start scanning for nearby peripherals.
    • Select the Nordic_Blinky peripheral that appears on screen (Note: if the peripheral does not show up, ensure that it's powered on and functional).
    • Your iOS device will now connect to the peripheral and state is displayed on the screen.
    • Changing the value of the Toggle switch will turn LED 3 on or off.
    • Pressing Button 1 on the Development Kit will show the button state as Pressed on the app.
    • Releasing Button 1 will show the state as Released on the App.


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0.8.0 - 2020-03-17 17:09:42

New features:

  • Option to reset peripheral
  • Sample app rewritten to use Notifications. This allows UI tests in Unit Tests.

Bugs fixed:

  • Fixed an issue, where some BLE operations were still possible after the device was out of range/reset (until the central manager got the callback).

Other improvements:

  • Unit tests improved

0.7.0 - 2020-03-06 15:09:52

Initial release.

Supported features:

  • All features from up to iOS 13 when using native CBCentralManager implementation.
  • Mocking scanning and connection.

Not supported features: