[WIP] Add visibleAnnotations API

platform/ios/app/MBXViewController.m

@@ -46,6 +46,7 @@ typedef NS_ENUM(NSInteger, MBXSettingsAnnotationsRows) {
     MBXSettingsAnnotations10000Sprites,
     MBXSettingsAnnotationsTestShapes,
     MBXSettingsAnnotationsCustomCallout,
+    MBXSettingsAnnotationsQueryAnnotations,
     MBXSettingsAnnotationsRemoveAnnotations,
 };
 
@@ -98,6 +99,11 @@ @interface MBXViewController () <UITableViewDelegate,
 @property (nonatomic) BOOL debugLoggingEnabled;
 @property (nonatomic) BOOL customUserLocationAnnnotationEnabled;
 
+@property (nonatomic) BOOL isTestingFeaturesInBox;
+@property (nonatomic) UIView *featuresInBoxView;
+@property (nonatomic) CLLocationCoordinate2D countPointCoordinate;
+@property (nonatomic) UILabel *countLabel;
+
 @end
 
 @implementation MBXViewController
@@ -289,6 +295,7 @@ - (void)dismissSettings:(__unused id)sender
                 @"Add 10,000 Sprites",
                 @"Add Test Shapes",
                 @"Add Point With Custom Callout",
+                @"Query Annotations",
                 @"Remove Annotations",
             ]];
             break;
@@ -387,6 +394,9 @@ - (void)performActionForSettingAtIndexPath:(NSIndexPath *)indexPath
                 case MBXSettingsAnnotationsCustomCallout:
                     [self addAnnotationWithCustomCallout];
                     break;
+                case MBXSettingsAnnotationsQueryAnnotations:
+                    [self testQueryPointAnnotations];
+                    break;
                 case MBXSettingsAnnotationsRemoveAnnotations:
                     [self.mapView removeAnnotations:self.mapView.annotations];
                     break;
@@ -875,6 +885,20 @@ - (void)toggleCustomUserDot
     self.mapView.userTrackingMode = MGLUserTrackingModeFollow;
 }
 
+- (void)testQueryPointAnnotations {
+    NSNumber *visibleAnnotationCount = @(self.mapView.visibleAnnotations.count);
+    NSString *message;
+    if ([visibleAnnotationCount integerValue] == 1) {
+        message = [NSString stringWithFormat:@"There is %@ visible annotation.", visibleAnnotationCount];
+    } else {
+        message = [NSString stringWithFormat:@"There are %@ visible annotations.", visibleAnnotationCount];
+    }
+
+    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Visible Annotations" message:message preferredStyle:UIAlertControllerStyleAlert];
+    [alertController addAction:[UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleCancel handler:nil]];
+    [self presentViewController:alertController animated:YES completion:nil];
+}
+
 - (void)printTelemetryLogFile
 {
     NSString *fileContents = [NSString stringWithContentsOfFile:[self telemetryDebugLogFilePath] encoding:NSUTF8StringEncoding error:nil];

platform/ios/src/MGLMapView.h

@@ -892,6 +892,16 @@ IB_DESIGNABLE
  */
 @property (nonatomic, readonly, nullable) NS_ARRAY_OF(id <MGLAnnotation>) *annotations;
 
+/**
+ The complete list of annotations associated with the receiver that are 
+ currently visible. (read-only)
+ 
+ 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;
+
 /**
  Adds an annotation to the map view.
  

platform/ios/src/MGLMapView.mm

@@ -2796,6 +2796,30 @@ - (void)removeStyleClass:(NSString *)styleClass
     return [NSArray arrayWithObjects:&annotations[0] count:annotations.size()];
 }
 
+- (nullable NS_ARRAY_OF(id <MGLAnnotation>) *)visibleAnnotations
+{
+    if (_annotationContextsByAnnotationTag.empty())
+    {
+        return nil;
+    }
+
+    std::vector<MGLAnnotationTag> annotationTags = [self annotationTagsInRect:self.bounds];
+    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
 {