disable the send button when text is empty (#2088)

Author: rnystrom

Classes/Issues/IssueTextActionsView.swift

@@ -97,7 +97,10 @@ final class IssueTextActionsView: UIView, UICollectionViewDataSource, UICollecti
 
     public var sendButtonEnabled: Bool {
         get { return sendButton.isEnabled }
-        set { sendButton.isEnabled = newValue }
+        set {
+            sendButton.isEnabled = newValue
+            sendButton.alpha = newValue ? 1 : 0.25
+        }
     }
 
     init(operations: [IssueTextActionOperation], showSendButton: Bool) {

Classes/Issues/IssuesViewController.swift

@@ -32,7 +32,8 @@ final class IssuesViewController:
     IssueNeckLoadSectionControllerDelegate,
     FlatCacheListener,
     IssueCommentSectionControllerDelegate,
-    IssueTextActionsViewSendDelegate {
+    IssueTextActionsViewSendDelegate,
+    MessageTextViewListener {
 
     private let client: GithubClient
     private let model: IssueDetailsModel
@@ -50,6 +51,7 @@ final class IssuesViewController:
 
     private var needsScrollToBottom = false
     private var lastTimelineElement: ListDiffable?
+    private var actions: IssueTextActionsView?
 
     // must fetch collaborator info from API before showing editing controls
     private var viewerIsCollaborator = false
@@ -183,6 +185,10 @@ final class IssuesViewController:
         // text input bar uses UIVisualEffectView, don't try to match it
         actions.backgroundColor = .clear
         actions.sendDelegate = self
+        self.actions = actions
+
+        actions.sendButtonEnabled = !messageView.textView.text.isEmpty
+        messageView.textView.add(listener: self)
 
         textActionsController.configure(client: client, textView: messageView.textView, actions: actions)
         textActionsController.viewController = self
@@ -600,4 +606,13 @@ final class IssuesViewController:
         }
     }
 
+    // MARK: MessageTextViewListener
+
+    func didChange(textView: MessageTextView) {
+        actions?.sendButtonEnabled = !textView.text.isEmpty
+    }
+
+    func didChangeSelection(textView: MessageTextView) {}
+    func willChangeRange(textView: MessageTextView, to range: NSRange) {}
+
 }