Add option to prefetch low-resolution tiles

2 files changed, 21 insertions, 0 deletions

diff --git a/platform/ios/src/MGLMapView.h b/platform/ios/src/MGLMapView.h
index 5930dc98c1..e3640ecdf0 100644
--- a/platform/ios/src/MGLMapView.h
+++ b/platform/ios/src/MGLMapView.h
@@ -352,6 +352,15 @@ MGL_EXPORT IB_DESIGNABLE
  */
 @property (nonatomic, assign) MGLMapViewPreferredFramesPerSecond preferredFramesPerSecond;
 
+/**
+ A Boolean value indicating whether the map should prefetch tiles.
+ 
+ Loads tiles at a lower zoom-level to pre-render a low resolution preview while more detailed tiles are loaded.
+ 
+ Default is YES.
+ */
+@property (nonatomic, assign) BOOL prefetchesTiles;
+
 @property (nonatomic) NSArray<NSString *> *styleClasses __attribute__((unavailable("Support for style classes has been removed.")));
 
 - (BOOL)hasStyleClass:(NSString *)styleClass __attribute__((unavailable("Support for style classes has been removed.")));
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 3eeffb9cbd..1afcd52d7c 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -2630,6 +2630,18 @@ public:
     }
 }
 
+- (void)setPrefetchesTiles:(BOOL)prefetchesTiles{
+    if(prefetchesTiles)
+    {
+        _mbglMap->setPrefetchZoomDelta(0);
+    }
+    else
+    {
+        //Reset to default value.
+        _mbglMap->setPrefetchZoomDelta(4);
+    }
+}
+
 #pragma mark - Accessibility -
 
 - (NSString *)accessibilityValue