A mobile management library for devices supporting nRF Connect Device Manager.



Platforms License Release Swift Package Manager Compatible

nRF Connect Device Manager

nRF Connect Device Manager library is compatible with Mcu Manager, a management subsystem supported by nRF Connect SDK, Zephyr and Apache Mynewt.

The library provides a transport agnostic implementation of the McuManager protocol. It contains a default implementation for BLE transport.

Minimum required iOS version is 9.0, originally released in Fall of 2015.


This repository is a fork of the McuManager iOS Library, which is no longer being supported by its original maintainer. As of 2021, we have taken ownership of the library, so all new features and bug fixes will be added here. Please, migrate your projects to point to this Git repsository in order to get future updates. See migration guide.


SPM or Swift Package Manager (Recommended)

In Xcode, go to File → Swift Packages → Add Package Dependency... and add


pod 'iOSMcuManagerLibrary'


McuManager is an application layer protocol used to manage and monitor microcontrollers running Apache Mynewt and Zephyr. More specifically, McuManagr implements over-the-air (OTA) firmware upgrades, log and stat collection, and file-system and configuration management.

Command Groups

McuManager are organized by functionality into command groups. In mcumgr-ios, command groups are called managers and extend the McuManager class. The managers (groups) implemented in mcumgr-ios are:

  • DefaultManager: Contains commands relevant to the OS. This includes task and memory pool statistics, device time read & write, and device reset.
  • ImageManager: Manage image state on the device and perform image uploads.
  • StatsManager: Read stats from the device.
  • ConfigManager: Read/Write config values on the device.
  • LogManager: Collect logs from the device.
  • CrashManager: Run crash tests on the device.
  • RunTestManager: Runs tests on the device.
  • FileSystemManager: Download/upload files from the device file system.
  • BasicManager: Send 'Erase App Settings' command to the device.

Firmware Upgrade

Firmware upgrade is generally a four step process performed using commands from the image and default commands groups: upload, test, reset, and confirm.

This library provides a FirmwareUpgradeManager as a convinience for upgrading the image running on a device.


A FirmwareUpgradeManager provides an easy way to perform firmware upgrades on a device. A FirmwareUpgradeManager must be initialized with an McuMgrTransport which defines the transport scheme and device. Once initialized, a FirmwareUpgradeManager can perform one firmware upgrade at a time. Firmware upgrades are started using the start(data: Data) method and can be paused, resumed, and canceled using pause(), resume(), and cancel() respectively.


// Initialize the BLE transporter using a scanned peripheral
let bleTransport = McuMgrBleTransport(cbPeripheral)

// Initialize the FirmwareUpgradeManager using the transport and a delegate
let dfuManager = FirmwareUpgradeManager(bleTransport, delegate)

// Start the firmware upgrade with the image data
dfuManager.start(data: imageData)

Firmware Upgrade Mode

McuManager firmware upgrades can actually be performed in few different ways. These different upgrade modes determine the commands sent after the upload step. The FirmwareUpgradeManager can be configured to perform these upgrade variations by setting the mode property. The different firmware upgrade modes are as follows:

  • .testAndConfirm: This mode is the default and recommended mode for performing upgrades due to it's ability to recover from a bad firmware upgrade. The process for this mode is upload, test, reset, confirm.
  • .confirmOnly: This mode is not recommended. If the device fails to boot into the new image, it will not be able to recover and will need to be re-flashed. The process for this mode is upload, confirm, reset.
  • .testOnly: This mode is useful if you want to run tests on the new image running before confirming it manually as the primary boot image. The process for this mode is upload, test, reset.

Firmware Upgrade State

FirmwareUpgradeManager acts as a simple, mostly linear state machine which is determined by the mode. As the manager moves through the firmware upgrade process, state changes are provided through the FirmwareUpgradeDelegate's upgradeStateDidChange method.

The FirmwareUpgradeManager contains an additional state, validate, which precedes the upload. The validate state checks the current image state of the device in an attempt to bypass certain states of the firmware upgrade. For example, if the image to upgrade to already exists in slot 1 on the device, the FirmwareUpgradeManager will skip upload and move directly to test (or confirm if .confirmOnly mode has been set) from validate. If the uploaded image is already active, and confirmed in slot 0, the upgrade will succeed immediately. In short, the validate state makes it easy to reattempt an upgrade without needing to re-upload the image or manually determine where to start.

Firmware Upgrade Configuration

nRF53 Dual-Core SoC Diagram, which supports all of these features.

In version 1.2, new features were introduced to speed-up the Upload speeds, mirroring the work first done on the Android side, and they're all available through the new FirmwareUpgradeConfiguration struct.

  • pipelineDepth: (Represented as 'Number of Buffers' in the Example App UI.) For values larger than 1, this enables the SMP Pipelining feature. It means multiple write packets are sent concurrently, thereby providing a large speed increase the higher the number of buffers the receiving device is configured with. Set to 1 (Number of Buffers = Disabled) by default.
  • byteAlignment: This is required when used in conjunction with SMP Pipelining. By fixing the size of each chunk of Data sent for the Firmware Upgrade, we can predict the receiving device's offset jumps and therefore smoothly send multiple Data packets at the same time. When SMP Pipelining is not being used (pipelineDepth set to 1), the library still performs Byte Alignment if set, but it is not required for updates to work. Set to ImageUploadAlignment.disabled by default.
  • reassemblyBufferSize: SMP Reassembly is another speed-improving feature. It works on devices running NCS 2.0 firmware or later, and is self-adjusting. Before the Upload starts, a request is sent via DefaultManager asking for MCU Manager Paremeters. If received, it means the firmware can accept data in chunks larger than the MTU Size, therefore also increasing speed. This property will reflect the size of the buffer on the receiving device, and the McuMgrBleTransport will be set to chunk the data down within the same Sequence Number, keeping each packet transmission within the MTU boundaries. There is no work required for SMP Reassembly to work - on devices not supporting it, the MCU Manager Paremeters request will fail, and the Upload will proceed assuming no reassembly capabilities.
  • eraseAppSettings: This is not a speed-related feature. Instead, setting this to true means all app data on the device, including Bond Information, Number of Steps, Login or anything else are all erased. If there are any major data changes to the new firmware after the update, like a complete change of functionality or a new update with different save structures, this is recommended. Set to true by default.


Setting logDelegate property in a manager gives access to low level logs, that can help debugging both the app and your device. Messages are logged on 6 log levels, from .debug to .error, and additionally contain a McuMgrLogCategory, which identifies the originating component. Additionally, the logDelegate property of McuMgrBleTransport provides access to the BLE Transport logs.


// Initialize the BLE transporter using a scanned peripheral
let bleTransport = McuMgrBleTransport(cbPeripheral)
bleTransporter.logDelegate = UIApplication.shared.delegate as? McuMgrLogDelegate

// Initialize the DeviceManager using the transport and a delegate
let deviceManager = DeviceManager(bleTransport, delegate)
deviceManager.logDelegate = UIApplication.shared.delegate as? McuMgrLogDelegate

// Send echo
deviceManger.echo("Hello World!", callback)

OSLog integration

McuMgrLogDelegate can be easily integrated with the Unified Logging System. An example is provided in the example app in the AppDelegate.swift. A McuMgrLogLevel extension that can be found in that file translates the log level to one of OSLogType levels. Similarly, McuMgrLogCategory extension converts the category to OSLog type.