Add activity indicator while joining room.

Signed-off-by: Ivan Sein <ivan@nextcloud.com>

VideoCalls/ChatPlaceholderView.h

@@ -10,4 +10,7 @@
 
 @interface ChatPlaceholderView : UIView
 
+@property (weak, nonatomic) IBOutlet UIView *placeholderView;
+@property (weak, nonatomic) IBOutlet UIActivityIndicatorView *loadingView;
+
 @end

VideoCalls/ChatPlaceholderView.xib

@@ -12,6 +12,8 @@
         <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner" customClass="ChatPlaceholderView">
             <connections>
                 <outlet property="contentView" destination="iN0-l3-epB" id="OnQ-or-tGk"/>
+                <outlet property="loadingView" destination="FB3-Ig-rQB" id="gOr-Ol-aYj"/>
+                <outlet property="placeholderView" destination="Vla-vD-TGa" id="56h-KR-IJ3"/>
             </connections>
         </placeholder>
         <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
@@ -37,6 +39,10 @@
                     </subviews>
                     <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                 </view>
+                <activityIndicatorView opaque="NO" contentMode="scaleToFill" horizontalHuggingPriority="750" verticalHuggingPriority="750" fixedFrame="YES" style="gray" translatesAutoresizingMaskIntoConstraints="NO" id="FB3-Ig-rQB">
+                    <rect key="frame" x="177" y="324" width="20" height="20"/>
+                    <autoresizingMask key="autoresizingMask" flexibleMinX="YES" flexibleMaxX="YES" flexibleMinY="YES" flexibleMaxY="YES"/>
+                </activityIndicatorView>
             </subviews>
             <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
             <point key="canvasLocation" x="29.5" y="-163.5"/>

VideoCalls/NCChatViewController.m

@@ -26,6 +26,7 @@
 @interface NCChatViewController ()
 
 @property (nonatomic, strong) NCRoom *room;
+@property (nonatomic, strong) ChatPlaceholderView *chatBackgroundView;
 @property (nonatomic, strong) NSMutableDictionary *messages;
 @property (nonatomic, strong) NSMutableArray *dateSections;
 @property (nonatomic, strong) NSMutableArray *mentions;
@@ -98,8 +99,10 @@
     [self.autoCompletionView registerClass:[ChatMessageTableViewCell class] forCellReuseIdentifier:AutoCompletionCellIdentifier];
     [self registerPrefixesForAutoCompletion:@[@"@"]];
     
-    ChatPlaceholderView *placeholder = [[ChatPlaceholderView alloc] init];
-    self.tableView.backgroundView = placeholder;
+    _chatBackgroundView = [[ChatPlaceholderView alloc] init];
+    [_chatBackgroundView.placeholderView setHidden:YES];
+    [_chatBackgroundView.loadingView startAnimating];
+    self.tableView.backgroundView = _chatBackgroundView;
 }
 
 - (void)viewWillAppear:(BOOL)animated
@@ -210,6 +213,10 @@
     }
     
     [roomController startReceivingChatMessages];
+    
+    [_chatBackgroundView.loadingView stopAnimating];
+    [_chatBackgroundView.loadingView setHidden:YES];
+    [_chatBackgroundView.placeholderView setHidden:NO];
 }
 
 - (void)didReceiveChatMessages:(NSNotification *)notification