Execute a CoAP request asynchronously.
The specified closure is invoked when the response is ready or an early error occurs.
If a response is available, the first parameter in the CoapResponseReceiver closure invocation is OK and the second parameter is set to the created CoapResponse.
If an early error occurs, the first parameter is set to an appropriate NabtoEdgeClientError and the second parameter is nil.
public func executeAsync(closure: @escaping CoapResponseReceiver)
- invoked when async operation completes