CoreBluetooth Namespace

APIs to interact with Bluetooth devices.


The CoreBluetooth namespace allows developers to work with Bluetooth Low Energy (Bluetooth LE) devices.

The Bluetooth LE model revolves around CoreBluetooth.CBPeer objects. There are two kinds of CoreBluetooth.CBPeer: CoreBluetooth.CBCentral objects that scan and consume data provided by CoreBluetooth.CBPeripheral objects that correspond to data-providing Bluetooth LE devices.

Generally, the iOS device will be in the CoreBluetooth.CBCentral role, but it is also possible to create apps in which the device is a CoreBluetooth.CBPeripheral.

The following example shows the typical initialization behavior of an app that consumes data from external Bluetooth LE devices. Applications that have a CoreBluetooth.CBCentral must have an associated CoreBluetooth.CBCentralManagerDelegate delegate object and must override it's CoreBluetooth.CBCentralManagerDelegate.UpdatedState method. The override must check the state of the CoreBluetooth.CBCentralManager and confirm that it is CoreBluetooth.CBCentralManagerState.PoweredOn.

Typically, applications will want to scan for Bluetooth LE peripherals. This is a high-energy function, so developers should call CoreBluetooth.CBManager.StopScan after finding the CoreBluetooth.CBPeripheral in which they are interested or after a certain amount of time.

C# Example

public class MySimpleCBCentralManagerDelegate : CBCentralManagerDelegate
		override public void UpdatedState (CBCentralManager mgr)
			if (mgr.State == CBCentralManagerState.PoweredOn) {
				//Passing in null scans for all peripherals. Peripherals can be targeted by using CBUIIDs
				CBUUID[] cbuuids = null;
				mgr.ScanForPeripherals (cbuuids); //Initiates async calls of DiscoveredPeripheral
				//Timeout after 30 seconds
				var timer = new Timer (30 * 1000);
				timer.Elapsed += (sender, e) => mgr.StopScan();
			} else {
				//Invalid state -- Bluetooth powered down, unavailable, etc.
				System.Console.WriteLine ("Bluetooth is not available");

		public override void DiscoveredPeripheral (CBCentralManager central, CBPeripheral peripheral, NSDictionary advertisementData, NSNumber RSSI)
			Console.WriteLine ("Discovered {0}, data {1}, RSSI {2}", peripheral.Name, advertisementData, RSSI);

public partial class HelloBluetoothCSharpViewController : UIViewController
    MySimpleCBCentralManagerDelegate myDel;

		public override void ViewDidLoad ()
			base.ViewDidLoad ();
      //Important to retain reference, else will be GC'ed
			myDel = new MySimpleCBCentralManagerDelegate ();
			var myMgr = new CBCentralManager (myDel, DispatchQueue.CurrentQueue);


The CoreBluetooth.CBCentralManagerDelegate.DiscoveredPeripheral method may be called multiple times for a single physical device. Once application developers have a reference to the CoreBluetooth.CBPeripheral in which they are interested, they should maintain that reference for further work and call CoreBluetooth.CBCentralManager.StopScan.

With a reference to a discovered CoreBluetooth.CBPeripheral, developers can then connect to it, as shown in the following example.

A CoreBluetooth.CBPeripheral has zero or more CoreBluetooth.CBServices, each of which has zero or more CoreBluetooth.CBCharacteristics. If the characteristic represents a measurement (such as a heartbeat, time, temperature, etc.), the value will be in the CoreBluetooth.CBCharacteristic.Value property.

C# Example

public class SimplePeripheralDelegate : CBPeripheralDelegate
	public override void DiscoveredService (CBPeripheral peripheral, NSError error)
		System.Console.WriteLine ("Discovered a service");
		foreach (var service in peripheral.Services) {
			Console.WriteLine (service.ToString ()); 
			peripheral.DiscoverCharacteristics (service);

	public override void DiscoveredCharacteristic (CBPeripheral peripheral, CBService service, NSError error)
		System.Console.WriteLine ("Discovered characteristics of " + peripheral);
		foreach (var c in service.Characteristics) {
			Console.WriteLine (c.ToString ());
			peripheral.ReadValue (c);

	public override void UpdatedValue (CBPeripheral peripheral, CBDescriptor descriptor, NSError error)
		Console.WriteLine ("Value of characteristic " + descriptor.Characteristic + " is " + descriptor.Value);

	public override void UpdatedCharacterteristicValue (CBPeripheral peripheral, CBCharacteristic characteristic, NSError error)
		Console.WriteLine ("Value of characteristic " + characteristic.ToString () + " is " + characteristic.Value);

mgr = new CBCentralManager (myCentralDelegate, DispatchQueue.CurrentQueue);

mgr.ConnectedPeripheral += (s, e) => {
	activePeripheral = e.Peripheral;
	System.Console.WriteLine ("Connected to " + activePeripheral.Name);

	if (activePeripheral.Delegate == null) {
		activePeripheral.Delegate = new SimplePeripheralDelegate ();
    //Begins asynchronous discovery of services
		activePeripheral.DiscoverServices ();

//Connect to peripheral, triggering call to ConnectedPeripheral event handled above 
mgr.ConnectPeripheral (myPeripheral);          


CBAdvertisementKeys used to lookup dictionary values from the NSDictionary received as a parameter in CoreBluetooth.CBCentralManagerDelegate.DiscoveredPeripheral.
CBATTErrorErrors returned by a GATT server.
CBATTRequestAn Attribute Protocol request for reading or writing.
CBATTRequestEventArgsProvides data for the CoreBluetooth.CBATTRequestEventArgs.ReadRequestReceived event.
CBATTRequestsEventArgsProvides data for the CoreBluetooth.CBATTRequestsEventArgs.WriteRequestsReceived event.
CBAttributeClass that uniquely identifies a Bluetooth device.
CBAttributePermissionsEnumerates the read, write, and encryption permissions for a characteristic's values.
CBCentralUsed to identify centrals (that are not the current device).
CBCentralInitOptionsContains options for initializing a Bluetooth central manager.
CBCentralManagerRepresents the local central device in Bluetooth LE.  Use the CBCentralManager to scan, discover and connect to remote peripherals.
CBCentralManagerDelegateDelegate objects for CoreBluetooth.CBCentralManager objects.
CBCentralManagerDelegate_ExtensionsExtension methods to the CoreBluetooth.ICBCentralManagerDelegate interface to support all the methods from the CoreBluetooth.CBCentralManagerDelegate protocol.
CBCentralManagerStateEnumerates possible states of a CoreBluetooth.CBCentralManager.
CBCharacteristicCharacteristics of a remote peripheral.
CBCharacteristicEventArgsProvides data for the CoreBluetooth.CBCharacteristicEventArgs.DiscoveredDescriptor, CoreBluetooth.CBCharacteristicEventArgs.UpdatedCharacterteristicValue, CoreBluetooth.CBCharacteristicEventArgs.UpdatedNotificationState and CoreBluetooth.CBCharacteristicEventArgs.WroteCharacteristicValue events.
CBCharacteristicPropertiesThe possible properties of a characteristic. A characteristic may have multiple properties.
CBCharacteristicWriteTypeEnumerates the possible types of writes to a characteristic's value.
CBDescriptorAn immutable description of a peripheral's characteristic. See also CoreBluetooth.CBMutableDescriptor.
CBDescriptorEventArgsProvides data for the CoreBluetooth.CBDescriptorEventArgs.UpdatedValue and CoreBluetooth.CBDescriptorEventArgs.WroteDescriptorValue events.
CBDiscoveredPeripheralEventArgsProvides data for the CoreBluetooth.CBDiscoveredPeripheralEventArgs.DiscoveredPeripheral event.
CBErrorErrors possible during Bluetooth LE transactions.
CBMutableCharacteristicA mutable CoreBluetooth.CBCharacteristic.
CBMutableDescriptorA mutable Corebluetooth.CBDescriptor.
CBMutableServiceA mutable Corebluetooth.CBService.
CBPeerClass that represents a central or perhipheral Bluetooth device.
CBPeripheralRepresents a CoreBluetooth peripheral.
CBPeripheralDelegateDelegate object for Corebluetooth.CBPeripheral. Provides methods called on events relating to discovery, exploration, and interaction with a remote peripheral.
CBPeripheralDelegate_ExtensionsExtension methods to the CoreBluetooth.ICBPeripheralDelegate interface to support all the methods from the CoreBluetooth.CBPeripheralDelegate protocol.
CBPeripheralErrorEventArgsProvides data for the CoreBluetooth.CBPeripheralErrorEventArgs.DisconnectedPeripheral and CoreBluetooth.CBPeripheralErrorEventArgs.FailedToConnectPeripheral events.
CBPeripheralEventArgsProvides data for the CoreBluetooth.CBPeripheralEventArgs.ConnectedPeripheral event.
CBPeripheralManagerManages published services per the Coreblutooth.CBPeripheral device's GATT database.
CBPeripheralManagerAuthorizationStatusEnumerates the possible states of the Corebluetooth.CBPeripheralManager.
CBPeripheralManagerConnectionLatencyThe connection latency of the Corebluetooth.CBPeripheralManager.
CBPeripheralManagerDelegateDelegate object for Corebluetooth.CBPeripheralManager. Adds methods for events relating to availability, publishing, advertising, and subscription.
CBPeripheralManagerDelegate_ExtensionsExtension methods to the CoreBluetooth.ICBPeripheralManagerDelegate interface to support all the methods from the CoreBluetooth.CBPeripheralManagerDelegate protocol.
CBPeripheralManagerServiceEventArgsProvides data for the CoreBluetooth.CBPeripheralManagerServiceEventArgs.ServiceAdded event.
CBPeripheralManagerStateEnumerates the possible states of the Corebluetooth.CBPeripheralManager.
CBPeripheralManagerSubscriptionEventArgsProvides data for the CoreBluetooth.CBPeripheralManagerSubscriptionEventArgs.CharacteristicSubscribed and CoreBluetooth.CBPeripheralManagerSubscriptionEventArgs.CharacteristicUnsubscribed events.
CBPeripheralServicesEventArgsProvides data for the CoreBluetooth.CBPeripheralServicesEventArgs.ModifiedServices event.
CBPeripheralsEventArgsProvides data for the CoreBluetooth.CBPeripheralsEventArgs.RetrievedConnectedPeripherals and CoreBluetooth.CBPeripheralsEventArgs.RetrievedPeripherals events.
CBPeripheralStateEnumerates the possible connection states of a Corebluetooth.CBPeripheral.
CBRssiEventArgsProvides data for the CoreBluetooth.CBRssiEventArgs.RssiRead event.
CBServiceRepresents the services of a remote peripheral.
CBServiceEventArgsProvides data for the CoreBluetooth.CBServiceEventArgs.DiscoverCharacteristic, CoreBluetooth.CBServiceEventArgs.DiscoveredCharacteristic and CoreBluetooth.CBServiceEventArgs.DiscoveredIncludedService events.
CBUUIDUniversal Unique Identifiers for the Bluetooth stack.
CBWillRestoreEventArgsProvides data for the CoreBluetooth.CBWillRestoreEventArgs.WillRestoreState and CoreBluetooth.CBWillRestoreEventArgs.WillRestoreState events.
ICBCentralManagerDelegateInterface representing the required methods (if any) of the protocol CoreBluetooth.CBCentralManagerDelegate.
ICBPeripheralDelegateInterface representing the required methods (if any) of the protocol CoreBluetooth.CBPeripheralDelegate.
ICBPeripheralManagerDelegateInterface representing the required methods (if any) of the protocol CoreBluetooth.CBPeripheralManagerDelegate.
PeripheralConnectionOptionsPeripheral connection options.
PeripheralScanningOptionsPossible values for the options parameter in calls to Corebluetooth.CBCentralManager.ScanForPeripherals.
StartAdvertisingOptionsManages access to options used by CoreBluetooth.StartAdvertising method.