Prepare Dark Theme

Observe user interface theme change.

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

Riot/ViewController/RecentsViewController.m

@@ -60,6 +60,9 @@
     // The fake search bar displayed at the top of the recents table. We switch on the actual search bar (self.recentsSearchBar)
     // when the user selects it.
     UISearchBar *tableSearchBar;
+    
+    // Observe kRiotDesignValuesDidChangeThemeNotification to handle user interface theme change.
+    id kRiotDesignValuesDidChangeThemeNotificationObserver;
 }
 
 @end
@@ -87,7 +90,6 @@
     [super finalizeInit];
     
     // Setup `MXKViewControllerHandling` properties
-    self.defaultBarTintColor = kRiotNavBarTintColor;
     self.enableBarTintColorStatusChange = NO;
     self.rageShakeManager = [RageShakeManager sharedManager];
     
@@ -143,6 +145,19 @@
     
     self.recentsSearchBar.autocapitalizationType = UITextAutocapitalizationTypeNone;
     self.recentsSearchBar.placeholder = NSLocalizedStringFromTable(@"search_default_placeholder", @"Vector", nil);
+    
+    // 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
@@ -168,6 +183,12 @@
         [[NSNotificationCenter defaultCenter] removeObserver:UIApplicationDidEnterBackgroundNotificationObserver];
         UIApplicationDidEnterBackgroundNotificationObserver = nil;
     }
+    
+    if (kRiotDesignValuesDidChangeThemeNotificationObserver)
+    {
+        [[NSNotificationCenter defaultCenter] removeObserver:kRiotDesignValuesDidChangeThemeNotificationObserver];
+        kRiotDesignValuesDidChangeThemeNotificationObserver = nil;
+    }
 }
 
 - (void)setEditing:(BOOL)editing animated:(BOOL)animated