[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).

platform/ios/CHANGELOG.md

@@ -26,6 +26,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 ### Annotations
 
 * Added a new initializer to `MGLAnnotationView` so that it is possible to create a new instance with an associated annotation object. ([#9029](https://github.com/mapbox/mapbox-gl-native/pull/9029))
+* Added a new `rotatesToMatchCamera` property to `MGLAnnotationView` that, when set to true, causes the annotation view to rotate along with the map's rotation angle giving the appearance that the annoation view is pinned to the map. ([#9147](https://github.com/mapbox/mapbox-gl-native/pull/9147))
 * Fixed an issue causing a view-backed annotation to disappear immediately instead of animating when the annotation’s `coordinate` property is set to a value outside the current viewport. ([#8565](https://github.com/mapbox/mapbox-gl-native/pull/8565))
 * Fixed an issue in which `MGLMapView` overrode the tint colors of its annotation views. ([#8789](https://github.com/mapbox/mapbox-gl-native/pull/8789))
 * Fixed an issue causing annotation views to persist in the map’s annotation container view even after their associated annotations were removed. ([#9025](https://github.com/mapbox/mapbox-gl-native/pull/9025))

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
 
 /**

platform/ios/src/MGLAnnotationView.mm

@@ -11,6 +11,7 @@ @interface MGLAnnotationView () <UIGestureRecognizerDelegate>
 
 @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 @@ - (instancetype)initWithCoder:(NSCoder *)decoder {
         _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 @@ - (void)encodeWithCoder:(NSCoder *)coder {
     [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 @@ - (void)setCenter:(CGPoint)center
 
     super.center = center;
     [self updateScaleTransformForViewingDistance];
+    [self updateRotateTransform];
 }
 
 - (void)setScalesWithViewingDistance:(BOOL)scalesWithViewingDistance
@@ -157,6 +161,26 @@ - (void)updateScaleTransformForViewingDistance
     }
 }
 
+- (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