Invoked when you retrieve a specified characteristic’s value, or when the peripheral device notifies your app that the characteristic’s value has changed.
- iOS 5.0+
- macOS 10.7+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 4.0+
- Core Bluetooth
The peripheral providing this information.
The characteristic whose value has been retrieved.
If an error occurred, the cause of the failure.
This method is invoked when your app calls the
read method, or when the peripheral notifies your app that the value of the characteristic for which notifications and indications are enabled (via a successful call to
set) has changed. If successful, the
error parameter is
nil. If unsuccessful, the
error parameter returns the cause of the failure.