init(type:properties:value:permissions:)

Declaration

init(type UUID: CBUUID, properties: CBCharacteristicProperties, value: Data?, permissions: CBAttributePermissions)

Parameters

• UUID:

  A 128-bit UUID that identifies the characteristic.

• properties:

  The properties of the characteristic.

• value:

  The characteristic value to cache. If nil, the value is dynamic and the peripheral manager fetches it on demand.

• permissions:

  The permissions of the characteristic value.

Return Value

A newly initialized mutable characteristic.

Discussion

If you specify a value for the characteristic, the characteristic caches the value and sets its properties and permissions to read and readable, respectively. Therefore, if you need the value of a characteristic to be writeable, or if you expect the value to change during the lifetime of the published service to which the characteristic belongs, you must specify the value as nil. This ensures that the characteristic treats the value dynamically. With a dynamic value, the peripheral manager requests the value whenever the peripheral manager receives a read or write request from a central. The peripheral does this by calling the peripheralManager(_:didReceiveRead:) and peripheralManager(_:didReceiveWrite:) methods of its delegate object, respectively.

For more information, see Core Bluetooth Programming Guide.