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# CBCentralManagerDelegate

A protocol that provides updates for the discovery and management of peripheral devices.

```
protocol CBCentralManagerDelegate : NSObjectProtocol
```

## Overview

The [`CBCentralManagerDelegate`](/documentation/CoreBluetooth/CBCentralManagerDelegate) protocol defines the methods that a delegate of a [`CBCentralManager`](/documentation/CoreBluetooth/CBCentralManager) object must adopt. The optional methods of the protocol allow the delegate to monitor the discovery, connectivity, and retrieval of peripheral devices. The only required method is [`centralManagerDidUpdateState(_:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManagerDidUpdateState(_:)); the central manager calls this when its state updates, thereby indicating the availability of the central manager.

## Topics

### Monitoring Connections with Peripherals

[`centralManager(_:didConnect:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManager(_:didConnect:))

Tells the delegate that the central manager connected to a peripheral.

[`centralManager(_:didDisconnectPeripheral:error:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManager(_:didDisconnectPeripheral:error:))

Tells the delegate that the central manager disconnected from a peripheral.

[`centralManager(_:didFailToConnect:error:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManager(_:didFailToConnect:error:))

Tells the delegate the central manager failed to create a connection with a peripheral.

[`centralManager(_:connectionEventDidOccur:for:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManager(_:connectionEventDidOccur:for:))

Tells the delegate that a connection event occurred which matches the registered options.

### Discovering and Retrieving Peripherals

[`centralManager(_:didDiscover:advertisementData:rssi:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManager(_:didDiscover:advertisementData:rssi:))

Tells the delegate the central manager discovered a peripheral while scanning for devices.

[Advertisement Data Retrieval Keys](/documentation/CoreBluetooth/advertisement-data-retrieval-keys)

Keys used to specify items in a dictionary of peripheral advertisement data.

### Monitoring the Central Manager’s State

[`centralManagerDidUpdateState(_:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManagerDidUpdateState(_:))

Tells the delegate the central manager’s state updated.

[`centralManager(_:willRestoreState:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManager(_:willRestoreState:))

Tells the delegate the system is about to restore the central manager.

### Monitoring the Central Manager’s Authorization

[`centralManager(_:didUpdateANCSAuthorizationFor:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManager(_:didUpdateANCSAuthorizationFor:))

Tells the delegate the authorization status changed for a ANCS-requiring connected peripheral.

### Instance Methods

[`centralManager(_:didDisconnectPeripheral:timestamp:isReconnecting:error:)`](/documentation/CoreBluetooth/CBCentralManagerDelegate/centralManager(_:didDisconnectPeripheral:timestamp:isReconnecting:error:))


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