---
title: "peripheral(_:didReadRSSI:error:)"
framework: corebluetooth
role: symbol
role_heading: Instance Method
path: "corebluetooth/cbperipheraldelegate/peripheral(_:didreadrssi:error:)"
---

# peripheral(_:didReadRSSI:error:)

Tells the delegate that retrieving the value of the peripheral’s current Received Signal Strength Indicator (RSSI) succeeded.

## Declaration

```swift
optional func peripheral(_ peripheral: CBPeripheral, didReadRSSI RSSI: NSNumber, error: (any Error)?)
```

## Parameters

- `peripheral`: The peripheral providing this information.
- `RSSI`: The RSSI, in decibels, of the peripheral.
- `error`: The reason the call failed, or nil if no error occurred.

## Discussion

Discussion Core Bluetooth invokes this method when your app calls the readRSSI() method, while the peripheral is connected to the central manager. If successful, the error parameter is nil and the parameter RSSI reports the peripheral’s signal strength, in decibels. If unsuccessful, the error parameter returns the cause of the failure.

## See Also

### Retrieving a Peripheral’s RSSI Data

- [peripheralDidUpdateRSSI(_:error:)](corebluetooth/cbperipheraldelegate/peripheraldidupdaterssi(_:error:).md)