Add ability to control Send button enabled state from external code.

ChattoAdditions/Source/Input/ChatInputBar.swift

@@ -38,6 +38,10 @@ public class ChatInputBar: ReusableXibView {
     public weak var delegate: ChatInputBarDelegate?
     weak var presenter: ChatInputBarPresenter?
 
+    public var updateSendButtonEnabledState = { (inputBar: ChatInputBar) -> Bool in
+        return !inputBar.textView.text.isEmpty
+    }
+
     @IBOutlet weak var scrollView: HorizontalStackScrollView!
     @IBOutlet weak var textView: ExpandableTextView!
     @IBOutlet weak var sendButton: UIButton!
@@ -145,10 +149,14 @@ public class ChatInputBar: ReusableXibView {
         }
         set {
             self.textView.text = newValue
-            self.sendButton.enabled = !self.textView.text.isEmpty
+            self.updateSendButton()
         }
     }
 
+    private func updateSendButton() {
+        self.sendButton.enabled = self.updateSendButtonEnabledState(self)
+    }
+
     @IBAction func buttonTapped(sender: AnyObject) {
         self.presenter?.onSendButtonPressed()
         self.delegate?.inputBarSendButtonPressed(self)
@@ -213,7 +221,7 @@ extension ChatInputBar: UITextViewDelegate {
     }
 
     public func textViewDidChange(textView: UITextView) {
-        self.sendButton.enabled = !textView.text.isEmpty
+        self.updateSendButton()
         self.delegate?.inputBarDidChangeText(self)
     }
 }

ChattoAdditions/Tests/Input/ChatInputBarTests.swift

@@ -141,6 +141,18 @@ class ChatInputBarTests: XCTestCase {
         self.bar.buttonTapped(self.bar)
         XCTAssertTrue(self.delegate.inputBarSendButtonPressedCalled)
     }
+
+    func testThat_WhenInputTextChangedAndCustomStateUpdateClosureProvided_BarUpdatesSendButtonStateAccordingly() {
+        var closureCalled = false
+        self.bar.updateSendButtonEnabledState = { (_) in
+            closureCalled = true
+            return false
+        }
+        self.bar.inputText = "    "
+        self.bar.textViewDidChange(self.bar.textView)
+        XCTAssertTrue(closureCalled)
+        XCTAssertFalse(self.bar.sendButton.enabled)
+    }
 }
 
 class FakeChatInputBarPresenter: ChatInputBarPresenter {