Fix for preloading textview and resizing it (#1865) close #1709

* Fix for behaviour described in issue #1709, where input toolbar and corresponding textView do not keep their old size when the view re-appears while a multi-line message is being entered.

Author: idrougge

JSQMessagesViewController/Controllers/JSQMessagesViewController.m

@@ -238,7 +238,9 @@ - (void)viewDidLoad
 - (void)viewWillAppear:(BOOL)animated
 {
     [super viewWillAppear:animated];
-    self.toolbarHeightConstraint.constant = self.inputToolbar.preferredDefaultHeight;
+    if (!self.inputToolbar.contentView.textView.hasText) {
+        self.toolbarHeightConstraint.constant = self.inputToolbar.preferredDefaultHeight;
+    }
     [self.view layoutIfNeeded];
     [self.collectionView.collectionViewLayout invalidateLayout];