I have an object that is an NSRuleEditorDelegate for an NSRuleEditor whose nestingMode is NSRuleEditorNestingModeList. There are 8 different possible criteria. Each criterion is optional but at least 1 is required (ruleEditor.canRemoveAllRows = NO). Each criterion should only be added once. How can I limit adding a criterion for a row if it is already in the editor at a different row? Thanks!

I'm using Network to establish a connection to various SMTP servers. For SMTP servers that use SSL on port 465, using the following code to establish the connection and communicate with the server works fine (read/write code omitted): nw_endpoint_t endpoint = nw_endpoint_create_host("smtp.example.com", "465"); nw_parameters_t parameters = nw_parameters_create_secure_tcp(NW_PARAMETERS_DEFAULT_CONFIGURATION, NW_PARAMETERS_DEFAULT_CONFIGURATION); nw_connection_t connection = nw_connection_create(endpoint, parameters); nw_connection_set_queue(connection, dispatch_get_main_queue()); nw_connection_set_state_changed_handler(connection, ^(nw_connection_state_t state, nw_error_t error) { //... } nw_connection_start(connection); For servers on port 587 that require an insecure connection at start then renegotiate a TLS handshake with the STARTTLS command, I change the parameters like so: nw_parameters_t parameters = nw_parameters_create_secure_tcp(NW_PARAMETERS_DISABLE_PROTOCOL, NW_PARAMETERS_DEFAULT_CONFIGURATION); This does allow me to establish the connection to the SMTP server but I'm stumped on how to initiate TLS on the established connection after invoking the STARTTLS command and receiving an OK response from the SMTP server. How do I add TLS options to an existing connected nw_connection_t connection?