fixes #3113: bring in MGLMapView via +load for Interface Builder

platform/ios/MGLAccountManager.m

@@ -18,6 +18,9 @@
 #pragma mark - Internal
 
 + (void)load {
+    // Load all referenced categories due to absence of -ObjC linker flag
+    [MGLCategoryLoader loadCategories];
+
     // Read the initial configuration from Info.plist. The shown-in-app setting
     // preempts the Settings bundle check in -[MGLMapboxEvents init] triggered
     // by setting the access token.
@@ -35,8 +38,6 @@
 // Can be called from any thread.
 //
 + (instancetype) sharedManager {
-    [MGLCategoryLoader loadCategories];
-
     if (NSProcessInfo.processInfo.mgl_isInterfaceBuilderDesignablesAgent) {
         return nil;
     }

platform/ios/MGLCategoryLoader.m

@@ -4,15 +4,21 @@
 #import "NSProcessInfo+MGLAdditions.h"
 #import "NSString+MGLAdditions.h"
 
-// https://github.com/mapbox/mapbox-gl-native/issues/2966
+#import "MGLMapView.h"
 
 @implementation MGLCategoryLoader
 
 + (void)loadCategories
 {
+    // https://github.com/mapbox/mapbox-gl-native/issues/2966
+    //
     mgl_linkBundleCategory();
     mgl_linkProcessCategory();
     mgl_linkStringCategory();
+
+    // https://github.com/mapbox/mapbox-gl-native/issues/3113
+    //
+    NSString *description = [MGLMapView description];
 }
 
 @end