[ios, macos] add tileset encoding option to darwin sources (#11274)

* add tileset encoding option to darwin sources

* correct style guide

* link out to dem encoding docs

* markdownify comments

1 files changed, 18 insertions, 0 deletions

diff --git a/platform/darwin/src/MGLTileSource.mm b/platform/darwin/src/MGLTileSource.mm
index bc985bd728..c37812ab8e 100644
--- a/platform/darwin/src/MGLTileSource.mm
+++ b/platform/darwin/src/MGLTileSource.mm
@@ -19,6 +19,7 @@ const MGLTileSourceOption MGLTileSourceOptionCoordinateBounds = @"MGLTileSourceO
 const MGLTileSourceOption MGLTileSourceOptionAttributionHTMLString = @"MGLTileSourceOptionAttributionHTMLString";
 const MGLTileSourceOption MGLTileSourceOptionAttributionInfos = @"MGLTileSourceOptionAttributionInfos";
 const MGLTileSourceOption MGLTileSourceOptionTileCoordinateSystem = @"MGLTileSourceOptionTileCoordinateSystem";
+const MGLTileSourceOption MGLTileSourceOptionDEMEncoding = @"MGLTileSourceOptionDEMEncoding";
 
 @implementation MGLTileSource
 
@@ -129,5 +130,22 @@ mbgl::Tileset MGLTileSetFromTileURLTemplates(NS_ARRAY_OF(NSString *) *tileURLTem
         }
     }
 
+    if (NSNumber *demEncodingNumber = options[MGLTileSourceOptionDEMEncoding]) {
+        if (![demEncodingNumber isKindOfClass:[NSValue class]]) {
+            [NSException raise:NSInvalidArgumentException
+                        format:@"MGLTileSourceOptionDEMEncoding must be set to an NSValue or NSNumber."];
+        }
+        MGLDEMEncoding demEncoding;
+        [demEncodingNumber getValue:&demEncoding];
+        switch (demEncoding) {
+            case MGLDEMEncodingMapbox:
+                tileSet.encoding = mbgl::Tileset::DEMEncoding::Mapbox;
+                break;
+            case MGLDEMEncodingTerrarium:
+                tileSet.encoding = mbgl::Tileset::DEMEncoding::Terrarium;
+                break;
+        }
+    }
+
     return tileSet;
 }