[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/MGLFillStyleLayer.mm b/platform/darwin/src/MGLFillStyleLayer.mm
index e16e3b2652..1f8b7402d8 100644
--- a/platform/darwin/src/MGLFillStyleLayer.mm
+++ b/platform/darwin/src/MGLFillStyleLayer.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 MGLFillStyleLayer ()
 
-@property (nonatomic) mbgl::style::FillLayer *layer;
+@property (nonatomic) mbgl::style::FillLayer *rawLayer;
 
 @end
 
 @implementation MGLFillStyleLayer
+{
+    std::unique_ptr<mbgl::style::FillLayer> _pendingLayer;
+}
 
 - (instancetype)initWithIdentifier:(NSString *)identifier source:(MGLSource *)source
 {
     if (self = [super initWithIdentifier:identifier source:source]) {
-        _layer = new mbgl::style::FillLayer(identifier.UTF8String, source.identifier.UTF8String);
+        auto layer = std::make_unique<mbgl::style::FillLayer>(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)setFillAntialias:(MGLStyleValue<NSNumber *> *)fillAntialias {
     auto mbglValue = MGLStyleValueTransformer<bool, NSNumber *>().toPropertyValue(fillAntialias);
-    self.layer->setFillAntialias(mbglValue);
+    self.rawLayer->setFillAntialias(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)fillAntialias {
-    auto propertyValue = self.layer->getFillAntialias() ?: self.layer->getDefaultFillAntialias();
+    auto propertyValue = self.rawLayer->getFillAntialias() ?: self.rawLayer->getDefaultFillAntialias();
     return MGLStyleValueTransformer<bool, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setFillOpacity:(MGLStyleValue<NSNumber *> *)fillOpacity {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(fillOpacity);
-    self.layer->setFillOpacity(mbglValue);
+    self.rawLayer->setFillOpacity(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)fillOpacity {
-    auto propertyValue = self.layer->getFillOpacity() ?: self.layer->getDefaultFillOpacity();
+    auto propertyValue = self.rawLayer->getFillOpacity() ?: self.rawLayer->getDefaultFillOpacity();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setFillColor:(MGLStyleValue<MGLColor *> *)fillColor {
     auto mbglValue = MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toPropertyValue(fillColor);
-    self.layer->setFillColor(mbglValue);
+    self.rawLayer->setFillColor(mbglValue);
 }
 
 - (MGLStyleValue<MGLColor *> *)fillColor {
-    auto propertyValue = self.layer->getFillColor() ?: self.layer->getDefaultFillColor();
+    auto propertyValue = self.rawLayer->getFillColor() ?: self.rawLayer->getDefaultFillColor();
     return MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toStyleValue(propertyValue);
 }
 
 - (void)setFillOutlineColor:(MGLStyleValue<MGLColor *> *)fillOutlineColor {
     auto mbglValue = MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toPropertyValue(fillOutlineColor);
-    self.layer->setFillOutlineColor(mbglValue);
+    self.rawLayer->setFillOutlineColor(mbglValue);
 }
 
 - (MGLStyleValue<MGLColor *> *)fillOutlineColor {
-    auto propertyValue = self.layer->getFillOutlineColor() ?: self.layer->getDefaultFillOutlineColor();
+    auto propertyValue = self.rawLayer->getFillOutlineColor() ?: self.rawLayer->getDefaultFillOutlineColor();
     return MGLStyleValueTransformer<mbgl::Color, MGLColor *>().toStyleValue(propertyValue);
 }
 
 - (void)setFillTranslate:(MGLStyleValue<NSValue *> *)fillTranslate {
     auto mbglValue = MGLStyleValueTransformer<std::array<float, 2>, NSValue *>().toPropertyValue(fillTranslate);
-    self.layer->setFillTranslate(mbglValue);
+    self.rawLayer->setFillTranslate(mbglValue);
 }
 
 - (MGLStyleValue<NSValue *> *)fillTranslate {
-    auto propertyValue = self.layer->getFillTranslate() ?: self.layer->getDefaultFillTranslate();
+    auto propertyValue = self.rawLayer->getFillTranslate() ?: self.rawLayer->getDefaultFillTranslate();
     return MGLStyleValueTransformer<std::array<float, 2>, NSValue *>().toStyleValue(propertyValue);
 }
 
 - (void)setFillTranslateAnchor:(MGLStyleValue<NSValue *> *)fillTranslateAnchor {
     auto mbglValue = MGLStyleValueTransformer<mbgl::style::TranslateAnchorType, NSValue *>().toPropertyValue(fillTranslateAnchor);
-    self.layer->setFillTranslateAnchor(mbglValue);
+    self.rawLayer->setFillTranslateAnchor(mbglValue);
 }
 
 - (MGLStyleValue<NSValue *> *)fillTranslateAnchor {
-    auto propertyValue = self.layer->getFillTranslateAnchor() ?: self.layer->getDefaultFillTranslateAnchor();
+    auto propertyValue = self.rawLayer->getFillTranslateAnchor() ?: self.rawLayer->getDefaultFillTranslateAnchor();
     return MGLStyleValueTransformer<mbgl::style::TranslateAnchorType, NSValue *>().toStyleValue(propertyValue);
 }
 
 - (void)setFillPattern:(MGLStyleValue<NSString *> *)fillPattern {
     auto mbglValue = MGLStyleValueTransformer<std::string, NSString *>().toPropertyValue(fillPattern);
-    self.layer->setFillPattern(mbglValue);
+    self.rawLayer->setFillPattern(mbglValue);
 }
 
 - (MGLStyleValue<NSString *> *)fillPattern {
-    auto propertyValue = self.layer->getFillPattern() ?: self.layer->getDefaultFillPattern();
+    auto propertyValue = self.rawLayer->getFillPattern() ?: self.rawLayer->getDefaultFillPattern();
     return MGLStyleValueTransformer<std::string, NSString *>().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