leave attribution at tile source level & consider all tile sources

@@ -13,6 +13,5 @@
 @interface RMAttributionViewController : UIViewController <UIWebViewDelegate>
 
 - (id)initWithMapView:(RMMapView *)mapView;
-- (id)initWithMapView:(RMMapView *)mapView customAttributionString:(NSString *)attributionString;
 
 @end

@@ -26,11 +26,6 @@
 
 - (id)initWithMapView:(RMMapView *)mapView
 {
-    return [self initWithMapView:mapView customAttributionString:nil];
-}
-
-- (id)initWithMapView:(RMMapView *)mapView customAttributionString:(NSString *)attributionString
-{
     self = [super initWithNibName:nil bundle:nil];
     
     if (self)
@@ -49,11 +44,22 @@
 
         webView.backgroundColor = [UIColor clearColor];
         webView.opaque = NO;
+
+        NSMutableString *attribution = [NSMutableString string];
+
+        for (id <RMTileSource>tileSource in mapView.tileSources)
+        {
+            if ([tileSource respondsToSelector:@selector(shortAttribution)])
+            {
+                if ([attribution length])
+                    [attribution appendString:@" "];
+
+                [attribution appendString:[tileSource shortAttribution]];
+            }
+        }
         
-        NSString *attribution = [mapView.tileSource shortAttribution];
-        
-        if ( ! attribution)
-            attribution = (attributionString ? attributionString : @"Map data © OpenStreetMap contributors <a href=\"http://mapbox.com/about/maps/\">(Details)</a>");
+        if ( ! [attribution length])
+              [attribution setString:@"Map data © OpenStreetMap contributors <a href=\"http://mapbox.com/about/maps/\">(Details)</a>"];
         
         NSMutableString *contentString = [NSMutableString string];