Prepare Dark Theme

Observe user interface theme change.

https://github.com/vector-im/riot-meta/issues/22

Riot/ViewController/RoomMessagesSearchViewController.m

@@ -32,6 +32,9 @@
 {
     // Observe kAppDelegateDidTapStatusBarNotification to handle tap on clock status bar.
     id kAppDelegateDidTapStatusBarNotificationObserver;
+    
+    // Observe kRiotDesignValuesDidChangeThemeNotification to handle user interface theme change.
+    id kRiotDesignValuesDidChangeThemeNotificationObserver;
 }
 
 @end
@@ -43,7 +46,6 @@
     [super finalizeInit];
     
     // Setup `MXKViewControllerHandling` properties
-    self.defaultBarTintColor = kRiotNavBarTintColor;
     self.enableBarTintColorStatusChange = NO;
     self.rageShakeManager = [RageShakeManager sharedManager];
 }
@@ -58,6 +60,30 @@
     // Reuse cells from the RoomViewController to display results
     [self.searchTableView registerClass:RoomIncomingTextMsgBubbleCell.class forCellReuseIdentifier:RoomIncomingTextMsgBubbleCell.defaultReuseIdentifier];
     [self.searchTableView registerClass:RoomIncomingAttachmentBubbleCell.class forCellReuseIdentifier:RoomIncomingAttachmentBubbleCell.defaultReuseIdentifier];
+    
+    // Observe user interface theme change.
+    kRiotDesignValuesDidChangeThemeNotificationObserver = [[NSNotificationCenter defaultCenter] addObserverForName:kRiotDesignValuesDidChangeThemeNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *notif) {
+        
+        [self userInterfaceThemeDidChange];
+        
+    }];
+    [self userInterfaceThemeDidChange];
+}
+
+- (void)userInterfaceThemeDidChange
+{
+    self.defaultBarTintColor = kRiotSecondaryBgColor;
+}
+
+- (void)destroy
+{
+    [super destroy];
+    
+    if (kRiotDesignValuesDidChangeThemeNotificationObserver)
+    {
+        [[NSNotificationCenter defaultCenter] removeObserver:kRiotDesignValuesDidChangeThemeNotificationObserver];
+        kRiotDesignValuesDidChangeThemeNotificationObserver = nil;
+    }
 }
 
 - (void)viewWillAppear:(BOOL)animated