[ios] Make annotation view rotation alignment configurable (#9147)

This commit adds `rotatesWithMap` property on `MGLAnnotationView`. This
property, when set to `YES` fixes the annotation to a map such that view
follows map's rotation angle. This is useful when user wants to display
rotation-dependent annotations (e.g. sector lights).

2 files changed, 37 insertions, 0 deletions

diff --git a/platform/ios/src/MGLAnnotationView.h b/platform/ios/src/MGLAnnotationView.h
index 9b17f05a6e..2802d31b05 100644
--- a/platform/ios/src/MGLAnnotationView.h
+++ b/platform/ios/src/MGLAnnotationView.h
@@ -171,6 +171,19 @@ typedef NS_ENUM(NSUInteger, MGLAnnotationViewDragState) {
  */
 @property (nonatomic, assign) BOOL scalesWithViewingDistance;
 
+/**
+ A Boolean value that determines whether the annotation view rotates together
+ with the map.
+
+ When the value of this property is `YES` and the map is rotated, the annotation
+ view rotates. This is also the behavior of `MGLAnnotationImage` objects. When the
+ value of this property is `NO` the annotation has its rotation angle fixed.
+
+ The default value of this property is `NO`. Set this property to `YES` if the
+ view’s rotation is important.
+ */
+@property (nonatomic, assign) BOOL rotatesToMatchCamera;
+
 #pragma mark Managing the Selection State
 
 /**
diff --git a/platform/ios/src/MGLAnnotationView.mm b/platform/ios/src/MGLAnnotationView.mm
index 78e38f10cb..94d0649413 100644
--- a/platform/ios/src/MGLAnnotationView.mm
+++ b/platform/ios/src/MGLAnnotationView.mm
@@ -11,6 +11,7 @@
 
 @property (nonatomic, readwrite, nullable) NSString *reuseIdentifier;
 @property (nonatomic, readwrite) CATransform3D lastAppliedScaleTransform;
+@property (nonatomic, readwrite) CATransform3D lastAppliedRotateTransform;
 @property (nonatomic, weak) UIPanGestureRecognizer *panGestureRecognizer;
 @property (nonatomic, weak) UILongPressGestureRecognizer *longPressRecognizer;
 @property (nonatomic, weak) MGLMapView *mapView;
@@ -53,6 +54,7 @@
         _annotation = [decoder decodeObjectOfClass:[NSObject class] forKey:@"annotation"];
         _centerOffset = [decoder decodeCGVectorForKey:@"centerOffset"];
         _scalesWithViewingDistance = [decoder decodeBoolForKey:@"scalesWithViewingDistance"];
+        _rotatesToMatchCamera = [decoder decodeBoolForKey:@"rotatesToMatchCamera"];
         _selected = [decoder decodeBoolForKey:@"selected"];
         _enabled = [decoder decodeBoolForKey:@"enabled"];
         self.draggable = [decoder decodeBoolForKey:@"draggable"];
@@ -66,6 +68,7 @@
     [coder encodeObject:_annotation forKey:@"annotation"];
     [coder encodeCGVector:_centerOffset forKey:@"centerOffset"];
     [coder encodeBool:_scalesWithViewingDistance forKey:@"scalesWithViewingDistance"];
+    [coder encodeBool:_rotatesToMatchCamera forKey:@"rotatesToMatchCamera"];
     [coder encodeBool:_selected forKey:@"selected"];
     [coder encodeBool:_enabled forKey:@"enabled"];
     [coder encodeBool:_draggable forKey:@"draggable"];
@@ -109,6 +112,7 @@
 
     super.center = center;
     [self updateScaleTransformForViewingDistance];
+    [self updateRotateTransform];
 }
 
 - (void)setScalesWithViewingDistance:(BOOL)scalesWithViewingDistance
@@ -157,6 +161,26 @@
     }
 }
 
+- (void)setRotatesToMatchCamera:(BOOL)rotatesToMatchCamera
+{
+    if (_rotatesToMatchCamera != rotatesToMatchCamera)
+    {
+        _rotatesToMatchCamera = rotatesToMatchCamera;
+        [self updateRotateTransform];
+    }
+}
+
+- (void)updateRotateTransform
+{
+    if (self.rotatesToMatchCamera == NO) return;
+
+    CGFloat directionRad = self.mapView.direction * M_PI / 180.0;
+    CATransform3D newRotateTransform = CATransform3DMakeRotation(-directionRad, 0, 0, 1);
+    self.layer.transform = CATransform3DConcat(CATransform3DIdentity, newRotateTransform);
+    
+    _lastAppliedRotateTransform = newRotateTransform;
+}
+
 #pragma mark - Draggable
 
 - (void)setDraggable:(BOOL)draggable