[ios, macos] Introduce visible annotations API (#6061)

Add visibleAnnotations API to make it easier for clients of MGLMapView
to query for all visible annotations in the map or all visible annotations
in a subsection of the map.

2 files changed, 50 insertions, 0 deletions

diff --git a/platform/macos/src/MGLMapView.h b/platform/macos/src/MGLMapView.h
index 3499671ff1..3dbbbe3d82 100644
--- a/platform/macos/src/MGLMapView.h
+++ b/platform/macos/src/MGLMapView.h
@@ -569,6 +569,16 @@ IB_DESIGNABLE
 - (void)addAnnotations:(NS_ARRAY_OF(id <MGLAnnotation>) *)annotations;
 
 /**
+ The complete list of annotations associated with the receiver that are
+ currently visible.
+ 
+ The objects in this array must adopt the `MGLAnnotation` protocol. If no
+ annotations are associated with the map view or if no annotations associated
+ with the map view are currently visible, the value of this property is `nil`.
+ */
+@property (nonatomic, readonly, nullable) NS_ARRAY_OF(id <MGLAnnotation>) *visibleAnnotations;
+
+/**
  Removes an annotation from the map view, deselecting it if it is selected.
  
  Removing an annotation object dissociates it from the map view entirely,
@@ -608,6 +618,17 @@ IB_DESIGNABLE
  */
 - (nullable MGLAnnotationImage *)dequeueReusableAnnotationImageWithIdentifier:(NSString *)identifier;
 
+/**
+ Returns the list of annotations associated with the receiver that intersect with
+ the given rectangle.
+ 
+ @param rect A rectangle expressed in the map view’s coordinate system.
+ @return An array of objects that adopt the `MGLAnnotation` protocol or `nil` if
+ no annotations associated with the map view are currently visible in the
+ rectangle.
+ */
+- (nullable NS_ARRAY_OF(id <MGLAnnotation>) *)visibleAnnotationsInRect:(CGRect)rect;
+
 #pragma mark Managing Annotation Selections
 
 /**
diff --git a/platform/macos/src/MGLMapView.mm b/platform/macos/src/MGLMapView.mm
index 14b83762a3..4d1f00359d 100644
--- a/platform/macos/src/MGLMapView.mm
+++ b/platform/macos/src/MGLMapView.mm
@@ -1616,6 +1616,35 @@ public:
     return [NSArray arrayWithObjects:&annotations[0] count:annotations.size()];
 }
 
+- (nullable NS_ARRAY_OF(id <MGLAnnotation>) *)visibleAnnotations
+{
+    return [self visibleFeaturesInRect:self.bounds];
+}
+
+- (nullable NS_ARRAY_OF(id <MGLAnnotation>) *)visibleAnnotationsInRect:(CGRect)rect
+{
+    if (_annotationContextsByAnnotationTag.empty())
+    {
+        return nil;
+    }
+    
+    std::vector<MGLAnnotationTag> annotationTags = [self annotationTagsInRect:rect];
+    if (annotationTags.size())
+    {
+        NSMutableArray *annotations = [NSMutableArray arrayWithCapacity:annotationTags.size()];
+        
+        for (auto const& annotationTag: annotationTags)
+        {
+            MGLAnnotationContext annotationContext = _annotationContextsByAnnotationTag[annotationTag];
+            [annotations addObject:annotationContext.annotation];
+        }
+        
+        return [annotations copy];
+    }
+    
+    return nil;
+}
+
 /// Returns the annotation assigned the given tag. Cheap.
 - (id <MGLAnnotation>)annotationWithTag:(MGLAnnotationTag)tag {
     if (!_annotationContextsByAnnotationTag.count(tag)) {