giveUpMentionUserAction for MessageToolbar to hide mentionView if it's not be use

Yep/ViewControllers/Conversation/ConversationViewController.swift

@@ -976,6 +976,10 @@ class ConversationViewController: BaseViewController {
                 }
             }
 
+            messageToolbar.giveUpMentionUserAction = { [weak self] in
+                self?.mentionView.hide()
+            }
+
             // 在这里才尝试恢复 messageToolbar 的状态，因为依赖 stateTransitionAction
     
             func tryRecoverMessageToolBar() {

Yep/Views/MessageToolbar/MessageToolbar.swift

@@ -144,6 +144,7 @@ class MessageToolbar: UIToolbar {
     var notifyTypingAction: (() -> Void)?
 
     var tryMentionUserAction: ((usernamePrefix: String) -> Void)?
+    var giveUpMentionUserAction: (() -> Void)?
 
     var textSendAction: ((messageToolBar: MessageToolbar) -> Void)?
 
@@ -494,8 +495,12 @@ extension MessageToolbar: UITextViewDelegate {
                     let usernamePrefix = lastPart.substringFromIndex(lastPart.startIndex.advancedBy(1))
                     mentionUsernameRange = text.rangeOfString(lastPart)
                     tryMentionUserAction?(usernamePrefix: usernamePrefix)
+
+                    return
                 }
             }
+
+            giveUpMentionUserAction?()
         }
     }
 }