Method peripheral: didWriteValueForCharacteristic: error: is not called

Question

I send data over BLE using the following call

[peripheral writeValue:dataPiece forCharacteristic:characteristic
    type:CBCharacteristicWriteWithResponse];

when the dataPiece size is 180 bytes or less everything works fine: accepting device receives all the data, on calling device corresponding callback (peripheral: didWriteValueForCharacteristic: error:) is called. When the size goes large (>180) receiving device still gets all the data (in two chunks: of 180 bytes and the rest). However in the latter case the callback on transmitting device is not called.

Also [peripheral maximumWriteValueLengthForType:CBCharacteristicWriteWithResponse] returns 512 which is more than 180, so I would expect 200 to work fine.

Am I missing something (obviously yes, but what)?

Answer 1

For peripheral, it should respond descriptor when central call readValueForDescriptor: method.
If it did not respond, central can not write data to it.

See:

• (void)readValueForDescriptor:(CBDescriptor *)descriptor;
• (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForDescriptor:(CBDescriptor *)descriptor error:(nullable NSError *)error;