Notifies the receiver that it’s been asked to relinquish its status as first responder.
YES if the text view will resign first responder,
If the object that will become the new first responder is a text view attached to the same layout manager as the receiver, this method returns
YES with no further action. Otherwise, this method sends a
text message to its delegate (if any). If the delegate returns
NO, this method returns
NO. If the delegate returns
YES, this method hides the selection highlighting and posts an
NSText to the default notification center and then returns
make, not this method, to make a text view the first responder. Never invoke this method directly.