4 files changed, 56 insertions, 14 deletions
diff --git a/platform/darwin/src/MGLFoundation.h b/platform/darwin/src/MGLFoundation.h
index be86bb92f9..3400c63979 100644
--- a/platform/darwin/src/MGLFoundation.h
+++ b/platform/darwin/src/MGLFoundation.h
@@ -3,10 +3,3 @@
 #import <Foundation/Foundation.h>
 
 #define MGL_EXPORT __attribute__((visibility ("default")))
-
-/* Using a compound statement (GNU Extension, supported by clang) */
-#define MGL_OBJC_DYNAMIC_CAST(object, type) \
-    ({ \
-        __typeof__( object ) temp##__LINE__ = (object); \
-        (type *)([temp##__LINE__ isKindOfClass:[type class]] ? temp##__LINE__ : nil); \
-    })
diff --git a/platform/darwin/src/MGLFoundation_Private.h b/platform/darwin/src/MGLFoundation_Private.h
index f231628756..71737c2cf9 100644
--- a/platform/darwin/src/MGLFoundation_Private.h
+++ b/platform/darwin/src/MGLFoundation_Private.h
@@ -3,3 +3,11 @@
 #include <mbgl/util/run_loop.hpp>
 
 void MGLInitializeRunLoop();
+
+/* Using a compound statement (GNU Extension, supported by clang) */
+#define MGL_OBJC_DYNAMIC_CAST(object, type) \
+    ({ \
+        __typeof__( object ) temp##__LINE__ = (object); \
+        (type *)([temp##__LINE__ isKindOfClass:[type class]] ? temp##__LINE__ : nil); \
+    })
+
diff --git a/platform/darwin/src/MGLRendererConfiguration.h b/platform/darwin/src/MGLRendererConfiguration.h
index d5b6527d7e..ea13582488 100644
--- a/platform/darwin/src/MGLRendererConfiguration.h
+++ b/platform/darwin/src/MGLRendererConfiguration.h
@@ -1,3 +1,4 @@
+#import "MGLFoundation.h"
 #import <Foundation/Foundation.h>
 #import <mbgl/storage/default_file_source.hpp>
 #import <mbgl/renderer/mode.hpp>
@@ -8,6 +9,7 @@ NS_ASSUME_NONNULL_BEGIN
  The MGLRendererConfiguration object represents configuration values for the
  renderer.
  */
+MGL_EXPORT
 @interface MGLRendererConfiguration : NSObject
 
 /** Returns an instance of the current renderer configuration. */
@@ -39,7 +41,9 @@ NS_ASSUME_NONNULL_BEGIN
  A Boolean value indicating whether symbol layers may enable per-source symbol
  collision detection.
  
- Set `MGLCollisionBehaviorPre4_0` in your containing app's Info.plist.
+ Set `MGLCollisionBehaviorPre4_0` in your containing app's Info.plist or by using
+ `[[NSUserDefaults standardUserDefaults] setObject:@(YES) forKey:@"MGLCollisionBehaviorPre4_0"]`.
+ If both are set, the value from `NSUserDefaults` takes priority.
  
  Setting this property to `YES` in the plist results in symbol layers only running
  collision detection against other symbol layers that are part of the same source.
diff --git a/platform/darwin/src/MGLRendererConfiguration.mm b/platform/darwin/src/MGLRendererConfiguration.mm
index b31da674cf..90778ea86d 100644
--- a/platform/darwin/src/MGLRendererConfiguration.mm
+++ b/platform/darwin/src/MGLRendererConfiguration.mm
@@ -1,5 +1,6 @@
 #import "MGLRendererConfiguration.h"
 #import "MGLOfflineStorage_Private.h"
+#import "MGLFoundation_Private.h"
 
 #if TARGET_OS_IPHONE
 #import <UIKit/UIKit.h>
@@ -7,6 +8,12 @@
 #import <AppKit/AppKit.h>
 #endif
 
+static NSString * const MGLCollisionBehaviorPre4_0Key = @"MGLCollisionBehaviorPre4_0";
+
+@interface MGLRendererConfiguration ()
+@property (nonatomic, readwrite) BOOL perSourceCollisions;
+@end
+
 
 @implementation MGLRendererConfiguration
 
@@ -14,6 +21,42 @@
     return [[self alloc] init];
 }
 
+- (instancetype)init {
+    return [self initWithPropertyDictionary:[[NSBundle mainBundle] infoDictionary]];
+}
+
+- (instancetype)initWithPropertyDictionary:(nonnull NSDictionary *)properties {
+    self = [super init];
+    
+    if (self) {
+        // Set the collision behaviour. A value set in `NSUserDefaults.standardUserDefaults`
+        // should override anything in the application's info.plist
+        NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
+
+        if ([defaults objectForKey:MGLCollisionBehaviorPre4_0Key]) {
+            _perSourceCollisions = [defaults boolForKey:MGLCollisionBehaviorPre4_0Key];
+        }
+        else {
+            id collisionBehaviourValue = properties[MGLCollisionBehaviorPre4_0Key];
+            
+            NSNumber *collisionBehaviourNumber = MGL_OBJC_DYNAMIC_CAST(collisionBehaviourValue, NSNumber);
+            
+            if (collisionBehaviourNumber) {
+                _perSourceCollisions = collisionBehaviourNumber.boolValue;
+            } else {
+                // Also support NSString to correspond with the behavior of `-[NSUserDefaults boolForKey:]`
+                NSString *collisionBehaviourString = MGL_OBJC_DYNAMIC_CAST(collisionBehaviourValue, NSString);
+
+                if (collisionBehaviourString) {
+                    _perSourceCollisions = collisionBehaviourString.boolValue;
+                }
+            }
+        }
+    }
+    
+    return self;
+}
+
 - (mbgl::DefaultFileSource *)fileSource {
     return [MGLOfflineStorage sharedOfflineStorage].mbglFileSource;
 }
@@ -40,10 +83,4 @@
     return fontFamilyName ? std::string([fontFamilyName UTF8String]) : mbgl::optional<std::string>();
 }
 
-- (BOOL)perSourceCollisions {
-    NSNumber *boolWrapper = [[[NSBundle mainBundle] infoDictionary] valueForKey:@"MGLCollisionBehaviorPre4_0"];
-    
-    return boolWrapper.boolValue;
-}
-
 @end