[ios, macos] Add overlays property to MGLMapView (#8617)

* Add `overlays` property to `MGLMapView.mm`

Implemented by filtering the `annotations` property for
annotations that conform to `MGLOverlay` protocol.

* Handle `nil` case when returning overlays

* Add basic documentation for `overlays` property

Copied verbatim from `annotations` property. Changed types.

* Add `overlays` property to iOS sdk

Implementation is identical to the one in macOS SDK.

* Match curly braces style

* Make `overlays` property `nonnull` on iOS

* Make `overlays` property `nonnull` on macOS

* Make cosmetic changes

* [ios, macos] Moved changelog entry to master

6 files changed, 52 insertions, 0 deletions

diff --git a/platform/ios/CHANGELOG.md b/platform/ios/CHANGELOG.md
index e8de9e3723..ceb371118d 100644
--- a/platform/ios/CHANGELOG.md
+++ b/platform/ios/CHANGELOG.md
@@ -5,6 +5,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 ## master
 
 * The previously-deprecated support for style classes has been removed. For interface compatibility, the API methods remain, but they are now non-functional.
+* Added an `overlays` property to `MGLMapView`. ([#8617](https://github.com/mapbox/mapbox-gl-native/pull/8617))
 
 ## 3.6.0
 
diff --git a/platform/ios/src/MGLMapView.h b/platform/ios/src/MGLMapView.h
index 8d26b1c90e..ca765a046b 100644
--- a/platform/ios/src/MGLMapView.h
+++ b/platform/ios/src/MGLMapView.h
@@ -1131,6 +1131,15 @@ IB_DESIGNABLE
 #pragma mark Overlaying the Map
 
 /**
+ The complete list of overlays associated with the receiver. (read-only)
+
+ The objects in this array must adopt the `MGLOverlay` protocol. If no
+ overlays are associated with the map view, the value of this property is
+ empty array.
+ */
+@property (nonatomic, readonly, nonnull) NS_ARRAY_OF(id <MGLOverlay>) *overlays;
+
+/**
  Adds a single overlay object to the map.
 
  To remove an overlay from a map, use the `-removeOverlay:` method.
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 8cba1187ea..d97c0b6602 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -3531,6 +3531,22 @@ public:
     }
 }
 
+- (nonnull NS_ARRAY_OF(id <MGLOverlay>) *)overlays
+{
+    if (self.annotations == nil) { return @[]; }
+
+    NS_MUTABLE_ARRAY_OF(id <MGLOverlay>) *mutableOverlays = [NSMutableArray array];
+
+    [self.annotations enumerateObjectsUsingBlock:^(id<MGLAnnotation>  _Nonnull annotation, NSUInteger idx, BOOL * _Nonnull stop) {
+        if ([annotation conformsToProtocol:@protocol(MGLOverlay)])
+        {
+            [mutableOverlays addObject:(id<MGLOverlay>)annotation];
+        }
+    }];
+
+    return [NSArray arrayWithArray:mutableOverlays];
+}
+
 - (void)addOverlay:(id <MGLOverlay>)overlay
 {
     [self addOverlays:@[ overlay ]];
diff --git a/platform/macos/CHANGELOG.md b/platform/macos/CHANGELOG.md
index 377c321452..579624f0e6 100644
--- a/platform/macos/CHANGELOG.md
+++ b/platform/macos/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## master
 
 * The previously-deprecated support for style classes has been removed. For interface compatibility, the API methods remain, but they are now non-functional.
+* Added an `overlays` property to `MGLMapView`. ([#8617](https://github.com/mapbox/mapbox-gl-native/pull/8617))
 
 ## 0.5.0
 
diff --git a/platform/macos/src/MGLMapView.h b/platform/macos/src/MGLMapView.h
index fb715a506d..6bfdcfd100 100644
--- a/platform/macos/src/MGLMapView.h
+++ b/platform/macos/src/MGLMapView.h
@@ -730,6 +730,15 @@ MGL_EXPORT IB_DESIGNABLE
 #pragma mark Overlaying the Map
 
 /**
+ The complete list of overlays associated with the receiver. (read-only)
+
+ The objects in this array must adopt the `MGLOverlay` protocol. If no
+ overlays are associated with the map view, the value of this property is
+ empty array.
+ */
+@property (nonatomic, readonly, nonnull) NS_ARRAY_OF(id <MGLOverlay>) *overlays;
+
+/**
  Adds a single overlay to the map.
 
  To remove an overlay from a map, use the `-removeOverlay:` method.
diff --git a/platform/macos/src/MGLMapView.mm b/platform/macos/src/MGLMapView.mm
index 59951f946d..98958f045d 100644
--- a/platform/macos/src/MGLMapView.mm
+++ b/platform/macos/src/MGLMapView.mm
@@ -2413,6 +2413,22 @@ public:
 
 #pragma mark Overlays
 
+- (nonnull NS_ARRAY_OF(id <MGLOverlay>) *)overlays
+{
+    if (self.annotations == nil) { return @[]; }
+
+    NS_MUTABLE_ARRAY_OF(id <MGLOverlay>) *mutableOverlays = [NSMutableArray array];
+
+    [self.annotations enumerateObjectsUsingBlock:^(id<MGLAnnotation>  _Nonnull annotation, NSUInteger idx, BOOL * _Nonnull stop) {
+        if ([annotation conformsToProtocol:@protocol(MGLOverlay)])
+        {
+            [mutableOverlays addObject:(id<MGLOverlay>)annotation];
+        }
+    }];
+
+    return [NSArray arrayWithArray:mutableOverlays];
+}
+
 - (void)addOverlay:(id <MGLOverlay>)overlay {
     [self addOverlays:@[overlay]];
 }