[ios, macos] Key-value compliance for MGLStyle

Replaced -[MGLMapView style] with a property. Keep the MGLStyle object around for the lifetime of the style.

Bracket changes to layers in willChange and didChange calls. The built-in point annotation layer is added after the style is finished loading but before the map is finished loading. Cause a second wave of change notifications to go out, about both sources and layers. Issue change notifications for style layers when shape annotations are added or removed.

2 files changed, 44 insertions, 12 deletions

diff --git a/platform/ios/src/MGLMapView.h b/platform/ios/src/MGLMapView.h
index e467495a4a..e066387e25 100644
--- a/platform/ios/src/MGLMapView.h
+++ b/platform/ios/src/MGLMapView.h
@@ -118,6 +118,14 @@ IB_DESIGNABLE
 #pragma mark Configuring the Map’s Appearance
 
 /**
+ The style currently displayed in the receiver.
+ 
+ Unlike the `styleURL` property, this property is set to an object that allows
+ you to manipulate every aspect of the style locally.
+ */
+@property (nonatomic, readonly) MGLStyle *style;
+
+/**
  URLs of the styles bundled with the library.
  
  @deprecated Call the relevant class method of `MGLStyle` for the URL of a
@@ -134,6 +142,9 @@ IB_DESIGNABLE
  
  If you set this property to `nil`, the receiver will use the default style
  and this property will automatically be set to that style’s URL.
+ 
+ If you want to modify the current style without replacing it outright, or if
+ you want to introspect individual style attributes, use the `style` property.
  */
 @property (nonatomic, null_resettable) NSURL *styleURL;
 
@@ -1077,10 +1088,6 @@ IB_DESIGNABLE
  */
 - (void)removeOverlays:(NS_ARRAY_OF(id <MGLOverlay>) *)overlays;
 
-#pragma mark - Runtime styling API
-
-- (MGLStyle *)style;
-
 #pragma mark Accessing the Underlying Map Data
 
 /**
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index e857a9fa4d..b1ecf1c415 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -236,6 +236,9 @@ public:
 @property (nonatomic, readwrite) UIButton *attributionButton;
 @property (nonatomic) NS_MUTABLE_ARRAY_OF(NSLayoutConstraint *) *attributionButtonConstraints;
 @property (nonatomic) UIActionSheet *attributionSheet;
+
+@property (nonatomic, readwrite) MGLStyle *style;
+
 @property (nonatomic) UIPanGestureRecognizer *pan;
 @property (nonatomic) UIPinchGestureRecognizer *pinch;
 @property (nonatomic) UIRotationGestureRecognizer *rotate;
@@ -284,6 +287,8 @@ public:
     std::vector<MGLAnnotationTag> _annotationsNearbyLastTap;
     CGPoint _initialImplicitCalloutViewOffset;
     NSDate *_userLocationAnimationCompletionDate;
+    /// True if a willChange notification has been issued for shape annotation layers and a didChange notification is pending.
+    BOOL _isChangingAnnotationLayers;
 
     BOOL _isWaitingForRedundantReachableNotification;
     BOOL _isTargetingInterfaceBuilder;
@@ -355,14 +360,17 @@ public:
 - (void)setStyleURL:(nullable NSURL *)styleURL
 {
     if (_isTargetingInterfaceBuilder) return;
-
+    
     if ( ! styleURL)
     {
         styleURL = [MGLStyle streetsStyleURLWithVersion:MGLStyleDefaultVersion];
     }
 
     styleURL = styleURL.mgl_URLByStandardizingScheme;
+    [self willChangeValueForKey:@"style"];
+    _style = [[MGLStyle alloc] initWithMapView:self];
     _mbglMap->setStyleURL([[styleURL absoluteString] UTF8String]);
+    [self didChangeValueForKey:@"style"];
 }
 
 - (IBAction)reloadStyle:(__unused id)sender {
@@ -620,13 +628,6 @@ public:
     return image;
 }
 
-- (MGLStyle *)style
-{
-    MGLStyle *style = [[MGLStyle alloc] init];
-    style.mapView = self;
-    return style;
-}
-
 - (void)reachabilityChanged:(NSNotification *)notification
 {
     MGLReachability *reachability = [notification object];
@@ -2895,6 +2896,7 @@ public:
                 continue;
             }
 
+            _isChangingAnnotationLayers = YES;
             MGLAnnotationTag annotationTag = _mbglMap->addAnnotation([multiPoint annotationObjectWithDelegate:self]);
             MGLAnnotationContext context;
             context.annotation = annotation;
@@ -2991,6 +2993,10 @@ public:
     [self updateAnnotationContainerViewWithAnnotationViews:newAnnotationViews];
 
     [self didChangeValueForKey:@"annotations"];
+    if (_isChangingAnnotationLayers)
+    {
+        [self.style willChangeValueForKey:@"layers"];
+    }
 
     if ([self.delegate respondsToSelector:@selector(mapView:didAddAnnotationViews:)])
     {
@@ -3213,11 +3219,16 @@ public:
             [(NSObject *)annotation removeObserver:self forKeyPath:@"coordinates" context:(void *)(NSUInteger)annotationTag];
         }
 
+        _isChangingAnnotationLayers = YES;
         _mbglMap->removeAnnotation(annotationTag);
     }
 
     [self didChangeValueForKey:@"annotations"];
     UIAccessibilityPostNotification(UIAccessibilityLayoutChangedNotification, nil);
+    if (_isChangingAnnotationLayers)
+    {
+        [self.style willChangeValueForKey:@"layers"];
+    }
 }
 
 - (void)addOverlay:(id <MGLOverlay>)overlay
@@ -4559,6 +4570,10 @@ public:
         }
         case mbgl::MapChangeDidFinishLoadingMap:
         {
+            [self.style willChangeValueForKey:@"sources"];
+            [self.style didChangeValueForKey:@"sources"];
+            [self.style willChangeValueForKey:@"layers"];
+            [self.style didChangeValueForKey:@"layers"];
             if ([self.delegate respondsToSelector:@selector(mapViewDidFinishLoadingMap:)])
             {
                 [self.delegate mapViewDidFinishLoadingMap:self];
@@ -4602,6 +4617,11 @@ public:
         case mbgl::MapChangeDidFinishRenderingFrame:
         case mbgl::MapChangeDidFinishRenderingFrameFullyRendered:
         {
+            if (_isChangingAnnotationLayers)
+            {
+                _isChangingAnnotationLayers = NO;
+                [self.style didChangeValueForKey:@"layers"];
+            }
             [self updateAnnotationViews];
             if ([self.delegate respondsToSelector:@selector(mapViewDidFinishRenderingFrame:fullyRendered:)])
             {
@@ -4611,6 +4631,11 @@ public:
         }
         case mbgl::MapChangeDidFinishLoadingStyle:
         {
+            [self.style willChangeValueForKey:@"name"];
+            [self.style willChangeValueForKey:@"sources"];
+            [self.style didChangeValueForKey:@"sources"];
+            [self.style willChangeValueForKey:@"layers"];
+            [self.style didChangeValueForKey:@"layers"];
             if ([self.delegate respondsToSelector:@selector(mapView:didFinishLoadingStyle:)])
             {
                 [self.delegate mapView:self didFinishLoadingStyle:self.style];