[ios, macos] Layer ownership refactor (#6904)

`MGLStyleLayer` was updated to support a raw pointer to the mbgl object, which is always initialized, either to the  value returned by `mbgl::Map getLayer`, or for independently created objects,  to the pointer value held in `pendingLayer`. In the latter case, this raw  pointer value stays even after ownership of the object is transferred via  `mbgl::Map addLayer`.

1 files changed, 45 insertions, 20 deletions

diff --git a/platform/darwin/src/MGLCircleStyleLayer.mm b/platform/darwin/src/MGLCircleStyleLayer.mm
index 8fe97a0537..13eedf3f96 100644
--- a/platform/darwin/src/MGLCircleStyleLayer.mm
+++ b/platform/darwin/src/MGLCircleStyleLayer.mm
@@ -2,6 +2,7 @@
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
 #import "MGLSource.h"
+#import "MGLMapView_Private.h"
 #import "NSPredicate+MGLAdditions.h"
 #import "MGLStyleLayer_Private.h"
 #import "MGLStyleValue_Private.h"
@@ -11,111 +12,135 @@
 
 @interface MGLCircleStyleLayer ()
 
-@property (nonatomic) mbgl::style::CircleLayer *layer;
+@property (nonatomic) mbgl::style::CircleLayer *rawLayer;
 
 @end
 
 @implementation MGLCircleStyleLayer
+{
+    std::unique_ptr<mbgl::style::CircleLayer> _pendingLayer;
+}
 
 - (instancetype)initWithIdentifier:(NSString *)identifier source:(MGLSource *)source
 {
     if (self = [super initWithIdentifier:identifier source:source]) {
-        _layer = new mbgl::style::CircleLayer(identifier.UTF8String, source.identifier.UTF8String);
+        auto layer = std::make_unique<mbgl::style::CircleLayer>(identifier.UTF8String, source.identifier.UTF8String);
+        _pendingLayer = std::move(layer);
+        self.rawLayer = _pendingLayer.get();
     }
     return self;
 }
 
+
 - (NSString *)sourceLayerIdentifier
 {
-    auto layerID = self.layer->getSourceLayer();
+    auto layerID = self.rawLayer->getSourceLayer();
     return layerID.empty() ? nil : @(layerID.c_str());
 }
 
 - (void)setSourceLayerIdentifier:(NSString *)sourceLayerIdentifier
 {
-    self.layer->setSourceLayer(sourceLayerIdentifier.UTF8String ?: "");
+    self.rawLayer->setSourceLayer(sourceLayerIdentifier.UTF8String ?: "");
 }
 
 - (void)setPredicate:(NSPredicate *)predicate
 {
-    self.layer->setFilter(predicate.mgl_filter);
+    self.rawLayer->setFilter(predicate.mgl_filter);
 }
 
 - (NSPredicate *)predicate
 {
-    return [NSPredicate mgl_predicateWithFilter:self.layer->getFilter()];
+    return [NSPredicate mgl_predicateWithFilter:self.rawLayer->getFilter()];
 }
 
 #pragma mark - Accessing the Paint Attributes
 
 - (void)setCircleRadius:(MGLStyleValue<NSNumber *> *)circleRadius {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(circleRadius);
-    self.layer->setCircleRadius(mbglValue);
+    self.rawLayer->setCircleRadius(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)circleRadius {
-    auto propertyValue = self.layer->getCircleRadius() ?: self.layer->getDefaultCircleRadius();
+    auto propertyValue = self.rawLayer->getCircleRadius() ?: self.rawLayer->getDefaultCircleRadius();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setCircleColor:(MGLStyleValue<MGLColor *> *)circleColor {
     auto mbglValue = MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toPropertyValue(circleColor);
-    self.layer->setCircleColor(mbglValue);
+    self.rawLayer->setCircleColor(mbglValue);
 }
 
 - (MGLStyleValue<MGLColor *> *)circleColor {
-    auto propertyValue = self.layer->getCircleColor() ?: self.layer->getDefaultCircleColor();
+    auto propertyValue = self.rawLayer->getCircleColor() ?: self.rawLayer->getDefaultCircleColor();
     return MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toStyleValue(propertyValue);
 }
 
 - (void)setCircleBlur:(MGLStyleValue<NSNumber *> *)circleBlur {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(circleBlur);
-    self.layer->setCircleBlur(mbglValue);
+    self.rawLayer->setCircleBlur(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)circleBlur {
-    auto propertyValue = self.layer->getCircleBlur() ?: self.layer->getDefaultCircleBlur();
+    auto propertyValue = self.rawLayer->getCircleBlur() ?: self.rawLayer->getDefaultCircleBlur();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setCircleOpacity:(MGLStyleValue<NSNumber *> *)circleOpacity {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(circleOpacity);
-    self.layer->setCircleOpacity(mbglValue);
+    self.rawLayer->setCircleOpacity(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)circleOpacity {
-    auto propertyValue = self.layer->getCircleOpacity() ?: self.layer->getDefaultCircleOpacity();
+    auto propertyValue = self.rawLayer->getCircleOpacity() ?: self.rawLayer->getDefaultCircleOpacity();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setCircleTranslate:(MGLStyleValue<NSValue *> *)circleTranslate {
     auto mbglValue = MGLStyleValueTransformer<std::array<float, 2>, NSValue *>().toPropertyValue(circleTranslate);
-    self.layer->setCircleTranslate(mbglValue);
+    self.rawLayer->setCircleTranslate(mbglValue);
 }
 
 - (MGLStyleValue<NSValue *> *)circleTranslate {
-    auto propertyValue = self.layer->getCircleTranslate() ?: self.layer->getDefaultCircleTranslate();
+    auto propertyValue = self.rawLayer->getCircleTranslate() ?: self.rawLayer->getDefaultCircleTranslate();
     return MGLStyleValueTransformer<std::array<float, 2>, NSValue *>().toStyleValue(propertyValue);
 }
 
 - (void)setCircleTranslateAnchor:(MGLStyleValue<NSValue *> *)circleTranslateAnchor {
     auto mbglValue = MGLStyleValueTransformer<mbgl::style::TranslateAnchorType, NSValue *>().toPropertyValue(circleTranslateAnchor);
-    self.layer->setCircleTranslateAnchor(mbglValue);
+    self.rawLayer->setCircleTranslateAnchor(mbglValue);
 }
 
 - (MGLStyleValue<NSValue *> *)circleTranslateAnchor {
-    auto propertyValue = self.layer->getCircleTranslateAnchor() ?: self.layer->getDefaultCircleTranslateAnchor();
+    auto propertyValue = self.rawLayer->getCircleTranslateAnchor() ?: self.rawLayer->getDefaultCircleTranslateAnchor();
     return MGLStyleValueTransformer<mbgl::style::TranslateAnchorType, NSValue *>().toStyleValue(propertyValue);
 }
 
 - (void)setCirclePitchScale:(MGLStyleValue<NSValue *> *)circlePitchScale {
     auto mbglValue = MGLStyleValueTransformer<mbgl::style::CirclePitchScaleType, NSValue *>().toPropertyValue(circlePitchScale);
-    self.layer->setCirclePitchScale(mbglValue);
+    self.rawLayer->setCirclePitchScale(mbglValue);
 }
 
 - (MGLStyleValue<NSValue *> *)circlePitchScale {
-    auto propertyValue = self.layer->getCirclePitchScale() ?: self.layer->getDefaultCirclePitchScale();
+    auto propertyValue = self.rawLayer->getCirclePitchScale() ?: self.rawLayer->getDefaultCirclePitchScale();
     return MGLStyleValueTransformer<mbgl::style::CirclePitchScaleType, NSValue *>().toStyleValue(propertyValue);
 }
 
+
+#pragma mark - Add style layer to map
+
+- (void)addToMapView:(MGLMapView *)mapView
+{
+    [self addToMapView:mapView belowLayer:nil];
+}
+
+- (void)addToMapView:(MGLMapView *)mapView belowLayer:(MGLStyleLayer *)otherLayer
+{
+    if (otherLayer) {
+        const mbgl::optional<std::string> belowLayerId{otherLayer.identifier.UTF8String};
+        mapView.mbglMap->addLayer(std::move(_pendingLayer), belowLayerId);
+    } else {
+        mapView.mbglMap->addLayer(std::move(_pendingLayer));
+    }
+}
+
 @end