[ios, macos] Make Xcode 7.3 the minimum required version

- Removes nullability shims for Xcode 6.
- Removes MGLTypes.h from files where it was only being used for
  nullability support.
- Accepts that `NS_SWIFT_NAME` is not fully supported by Xcode 7.2 and
  lower.
- Adds documentation about Xcode 7.3 requirement.

47 files changed, 25 insertions, 79 deletions

diff --git a/platform/darwin/src/MGLAccountManager.h b/platform/darwin/src/MGLAccountManager.h
index 2a11b2869e..fe602aa210 100644
--- a/platform/darwin/src/MGLAccountManager.h
+++ b/platform/darwin/src/MGLAccountManager.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLAnnotation.h b/platform/darwin/src/MGLAnnotation.h
index 7293aeec4f..4c8f600240 100644
--- a/platform/darwin/src/MGLAnnotation.h
+++ b/platform/darwin/src/MGLAnnotation.h
@@ -2,8 +2,6 @@
 #import <CoreLocation/CoreLocation.h>
 #import <TargetConditionals.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLBackgroundStyleLayer.h b/platform/darwin/src/MGLBackgroundStyleLayer.h
index 4b0fddeceb..8fa9abddec 100644
--- a/platform/darwin/src/MGLBackgroundStyleLayer.h
+++ b/platform/darwin/src/MGLBackgroundStyleLayer.h
@@ -1,7 +1,6 @@
 // This file is generated. 
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
-#import "MGLTypes.h"
 #import "MGLStyleAttributeValue.h"
 #import "MGLBaseStyleLayer.h"
 
diff --git a/platform/darwin/src/MGLCircleStyleLayer.h b/platform/darwin/src/MGLCircleStyleLayer.h
index eaab3b843d..c5a344d419 100644
--- a/platform/darwin/src/MGLCircleStyleLayer.h
+++ b/platform/darwin/src/MGLCircleStyleLayer.h
@@ -1,7 +1,6 @@
 // This file is generated. 
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
-#import "MGLTypes.h"
 #import "MGLStyleAttributeValue.h"
 #import "MGLBaseStyleLayer.h"
 
diff --git a/platform/darwin/src/MGLClockDirectionFormatter.h b/platform/darwin/src/MGLClockDirectionFormatter.h
index e467b20e06..ea427aa7b1 100644
--- a/platform/darwin/src/MGLClockDirectionFormatter.h
+++ b/platform/darwin/src/MGLClockDirectionFormatter.h
@@ -1,8 +1,6 @@
 #import <Foundation/Foundation.h>
 #import <CoreLocation/CoreLocation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLCompassDirectionFormatter.h b/platform/darwin/src/MGLCompassDirectionFormatter.h
index c2a6e000fa..fde26ba42a 100644
--- a/platform/darwin/src/MGLCompassDirectionFormatter.h
+++ b/platform/darwin/src/MGLCompassDirectionFormatter.h
@@ -1,8 +1,6 @@
 #import <Foundation/Foundation.h>
 #import <CoreLocation/CoreLocation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLCoordinateFormatter.h b/platform/darwin/src/MGLCoordinateFormatter.h
index 3759576d2a..909c1e8935 100644
--- a/platform/darwin/src/MGLCoordinateFormatter.h
+++ b/platform/darwin/src/MGLCoordinateFormatter.h
@@ -1,8 +1,6 @@
 #import <Foundation/Foundation.h>
 #import <CoreLocation/CoreLocation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLFeature.h b/platform/darwin/src/MGLFeature.h
index 1ab587ede5..aec4223b12 100644
--- a/platform/darwin/src/MGLFeature.h
+++ b/platform/darwin/src/MGLFeature.h
@@ -5,8 +5,6 @@
 #import "MGLPointAnnotation.h"
 #import "MGLShapeCollection.h"
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLFillStyleLayer.h b/platform/darwin/src/MGLFillStyleLayer.h
index 06a58b12bd..de5369a333 100644
--- a/platform/darwin/src/MGLFillStyleLayer.h
+++ b/platform/darwin/src/MGLFillStyleLayer.h
@@ -1,7 +1,6 @@
 // This file is generated. 
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
-#import "MGLTypes.h"
 #import "MGLStyleAttributeValue.h"
 #import "MGLBaseStyleLayer.h"
 
diff --git a/platform/darwin/src/MGLGeometry.h b/platform/darwin/src/MGLGeometry.h
index ca99eaf16f..5fc927697b 100644
--- a/platform/darwin/src/MGLGeometry.h
+++ b/platform/darwin/src/MGLGeometry.h
@@ -2,8 +2,6 @@
 #import <CoreLocation/CoreLocation.h>
 #import <CoreGraphics/CGBase.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /** Defines the area spanned by an `MGLCoordinateBounds`. */
diff --git a/platform/darwin/src/MGLLineStyleLayer.h b/platform/darwin/src/MGLLineStyleLayer.h
index 6f3472b0b3..812e759ebc 100644
--- a/platform/darwin/src/MGLLineStyleLayer.h
+++ b/platform/darwin/src/MGLLineStyleLayer.h
@@ -1,7 +1,6 @@
 // This file is generated. 
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
-#import "MGLTypes.h"
 #import "MGLStyleAttributeValue.h"
 #import "MGLBaseStyleLayer.h"
 
diff --git a/platform/darwin/src/MGLMapCamera.h b/platform/darwin/src/MGLMapCamera.h
index 4b50c32b2f..f6bff36280 100644
--- a/platform/darwin/src/MGLMapCamera.h
+++ b/platform/darwin/src/MGLMapCamera.h
@@ -2,8 +2,6 @@
 #import <CoreGraphics/CoreGraphics.h>
 #import <CoreLocation/CoreLocation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLMultiPoint.h b/platform/darwin/src/MGLMultiPoint.h
index 2d6b327086..59d9cd9429 100644
--- a/platform/darwin/src/MGLMultiPoint.h
+++ b/platform/darwin/src/MGLMultiPoint.h
@@ -3,8 +3,6 @@
 
 #import "MGLShape.h"
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLMultiPoint_Private.h b/platform/darwin/src/MGLMultiPoint_Private.h
index aa52a02fcb..dc39172723 100644
--- a/platform/darwin/src/MGLMultiPoint_Private.h
+++ b/platform/darwin/src/MGLMultiPoint_Private.h
@@ -1,7 +1,6 @@
 #import "MGLMultiPoint.h"
 
 #import "MGLGeometry.h"
-#import "MGLTypes.h"
 
 #import <mbgl/annotation/annotation.hpp>
 #import <vector>
diff --git a/platform/darwin/src/MGLOfflineRegion.h b/platform/darwin/src/MGLOfflineRegion.h
index cf98e253bd..fe0ab6cb7f 100644
--- a/platform/darwin/src/MGLOfflineRegion.h
+++ b/platform/darwin/src/MGLOfflineRegion.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLOverlay.h b/platform/darwin/src/MGLOverlay.h
index ba03b19737..382305b444 100644
--- a/platform/darwin/src/MGLOverlay.h
+++ b/platform/darwin/src/MGLOverlay.h
@@ -4,8 +4,6 @@
 #import "MGLAnnotation.h"
 #import "MGLGeometry.h"
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLPointAnnotation.h b/platform/darwin/src/MGLPointAnnotation.h
index 13afcab717..b552912f97 100644
--- a/platform/darwin/src/MGLPointAnnotation.h
+++ b/platform/darwin/src/MGLPointAnnotation.h
@@ -3,8 +3,6 @@
 
 #import "MGLShape.h"
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLRasterStyleLayer.h b/platform/darwin/src/MGLRasterStyleLayer.h
index e666862339..b9deed8ff4 100644
--- a/platform/darwin/src/MGLRasterStyleLayer.h
+++ b/platform/darwin/src/MGLRasterStyleLayer.h
@@ -1,7 +1,6 @@
 // This file is generated. 
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
-#import "MGLTypes.h"
 #import "MGLStyleAttributeValue.h"
 #import "MGLBaseStyleLayer.h"
 
diff --git a/platform/darwin/src/MGLShape.h b/platform/darwin/src/MGLShape.h
index 40c92fc32d..ce9375c910 100644
--- a/platform/darwin/src/MGLShape.h
+++ b/platform/darwin/src/MGLShape.h
@@ -2,8 +2,6 @@
 
 #import "MGLAnnotation.h"
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/darwin/src/MGLStyle.h b/platform/darwin/src/MGLStyle.h
index a8b36ab0ca..3354d27a43 100644
--- a/platform/darwin/src/MGLStyle.h
+++ b/platform/darwin/src/MGLStyle.h
@@ -1,9 +1,9 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 #import "MGLStyleLayer.h"
 
+#import "MGLTypes.h"
+
 @class MGLSource;
 
 NS_ASSUME_NONNULL_BEGIN
diff --git a/platform/darwin/src/MGLStyleAttribute.mm b/platform/darwin/src/MGLStyleAttribute.mm
index 38c212ddd4..8c51f80758 100644
--- a/platform/darwin/src/MGLStyleAttribute.mm
+++ b/platform/darwin/src/MGLStyleAttribute.mm
@@ -3,6 +3,8 @@
 #import "MGLStyleAttributeValue_Private.h"
 #import "MGLStyleAttributeFunction_Private.h"
 
+#import "MGLTypes.h"
+
 @interface MGLStyleAttribute()
 @end
 
diff --git a/platform/darwin/src/MGLStyleAttributeValue.h b/platform/darwin/src/MGLStyleAttributeValue.h
index 31edccb14f..cd33923889 100644
--- a/platform/darwin/src/MGLStyleAttributeValue.h
+++ b/platform/darwin/src/MGLStyleAttributeValue.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 @protocol MGLStyleAttributeValue <NSObject>
 @optional
 @end
\ No newline at end of file
diff --git a/platform/darwin/src/MGLStyleAttributeValue_Private.h b/platform/darwin/src/MGLStyleAttributeValue_Private.h
index 5fd51d09cf..3051f663d7 100644
--- a/platform/darwin/src/MGLStyleAttributeValue_Private.h
+++ b/platform/darwin/src/MGLStyleAttributeValue_Private.h
@@ -1,6 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
 #import "MGLStyleAttributeFunction_Private.h"
 
 #include <array>
diff --git a/platform/darwin/src/MGLStyleLayer.h.ejs b/platform/darwin/src/MGLStyleLayer.h.ejs
index 629edba6c6..4ef28469f1 100644
--- a/platform/darwin/src/MGLStyleLayer.h.ejs
+++ b/platform/darwin/src/MGLStyleLayer.h.ejs
@@ -6,7 +6,6 @@
 // This file is generated. 
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
-#import "MGLTypes.h"
 #import "MGLStyleAttributeValue.h"
 #import "MGLBaseStyleLayer.h"
 
diff --git a/platform/darwin/src/MGLStyleLayer.mm b/platform/darwin/src/MGLStyleLayer.mm
index 6703226cba..43d98d62dc 100644
--- a/platform/darwin/src/MGLStyleLayer.mm
+++ b/platform/darwin/src/MGLStyleLayer.mm
@@ -1,5 +1,4 @@
 #import "MGLStyleLayer.h"
 
-#import "MGLTypes.h"
 #import "MGLStyleLayer_Private.h"
 #import "MGLMapView_Private.h"
diff --git a/platform/darwin/src/MGLSymbolStyleLayer.h b/platform/darwin/src/MGLSymbolStyleLayer.h
index 1f3568890b..371107226f 100644
--- a/platform/darwin/src/MGLSymbolStyleLayer.h
+++ b/platform/darwin/src/MGLSymbolStyleLayer.h
@@ -1,7 +1,6 @@
 // This file is generated. 
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
-#import "MGLTypes.h"
 #import "MGLStyleAttributeValue.h"
 #import "MGLBaseStyleLayer.h"
 
diff --git a/platform/darwin/src/MGLTypes.h b/platform/darwin/src/MGLTypes.h
index f63c602a53..bc1889c96c 100644
--- a/platform/darwin/src/MGLTypes.h
+++ b/platform/darwin/src/MGLTypes.h
@@ -2,16 +2,6 @@
 
 #pragma once
 
-#if !__has_feature(nullability)
-    #define NS_ASSUME_NONNULL_BEGIN
-    #define NS_ASSUME_NONNULL_END
-    #define nullable
-    #define nonnull
-    #define null_resettable
-    #define _Nullable
-    #define _Nonnull
-#endif
-
 #if TARGET_OS_IPHONE
 @class UIColor;
 #define MGLColor UIColor
diff --git a/platform/darwin/src/NSData+MGLAdditions.h b/platform/darwin/src/NSData+MGLAdditions.h
index 0c68c81f45..38af7961b6 100644
--- a/platform/darwin/src/NSData+MGLAdditions.h
+++ b/platform/darwin/src/NSData+MGLAdditions.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 @interface NSData (MGLAdditions)
diff --git a/platform/darwin/src/NSString+MGLAdditions.h b/platform/darwin/src/NSString+MGLAdditions.h
index 3001624d32..5b549affd5 100644
--- a/platform/darwin/src/NSString+MGLAdditions.h
+++ b/platform/darwin/src/NSString+MGLAdditions.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 @interface NSString (MGLAdditions)
diff --git a/platform/darwin/src/NSURL+MGLAdditions.h b/platform/darwin/src/NSURL+MGLAdditions.h
index 70fd79f064..9845a180db 100644
--- a/platform/darwin/src/NSURL+MGLAdditions.h
+++ b/platform/darwin/src/NSURL+MGLAdditions.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 @interface NSURL (MGLAdditions)
diff --git a/platform/ios/CHANGELOG.md b/platform/ios/CHANGELOG.md
index 49e6369b6f..41afd5403d 100644
--- a/platform/ios/CHANGELOG.md
+++ b/platform/ios/CHANGELOG.md
@@ -6,6 +6,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 
 * A new runtime styling API allows you to adjust the style and content of the base map dynamically. All the options available in [Mapbox Studio](https://www.mapbox.com/studio/) are now exposed via MGLStyle and subclasses of MGLStyleLayer and MGLSource. ([#5727](https://github.com/mapbox/mapbox-gl-native/pull/5727))
 * The user location annotation is now customizable via the newly added `MGLUserLocationAnnotationView` class. ([#5882](https://github.com/mapbox/mapbox-gl-native/pull/5882))
+* Xcode 7.3 or higher is now required to use this SDK. ([#6059](https://github.com/mapbox/mapbox-gl-native/issues/6059))
 * Simulator architecture slices are included in the included dSYM file, allowing you to symbolicate crashes that occur in the Simulator. ([#5740](https://github.com/mapbox/mapbox-gl-native/pull/5740))
 * As the user zooms in, tiles from lower zoom levels are scaled up until tiles for higher zoom levels are loaded. ([#5143](https://github.com/mapbox/mapbox-gl-native/pull/5143))
 * Fixed an issue causing the wrong annotation view to be selected when tapping an annotation view with a center offset applied. ([#5931](https://github.com/mapbox/mapbox-gl-native/pull/5931))
diff --git a/platform/ios/DEVELOPING.md b/platform/ios/DEVELOPING.md
index 5ba6871959..704a357ce6 100644
--- a/platform/ios/DEVELOPING.md
+++ b/platform/ios/DEVELOPING.md
@@ -6,6 +6,8 @@ This document explains how to build the Mapbox iOS SDK from source. It is intend
 
 The Mapbox iOS SDK and iosapp demo application build against the iOS 7.0 SDK. The SDK is intended to run on iOS 7.0 and above, while iosapp is intended to run on iOS 8.0 and above due to the use of a dynamic framework. Both require Xcode on a computer running macOS.
 
+The Mapbox iOS SDK requires Xcode 7.3 or higher.
+
 ## Building the SDK
 
 Make sure that you have the [core dependencies](../../INSTALL.md) installed.
@@ -83,6 +85,7 @@ To add an Objective-C class, protocol, category, typedef, enumeration, or global
 To add an Objective-C header or implementation file to the iOS SDK:
 
 1. Add the file to the Headers or Compile Sources build phase, as appropriate, of both the “dynamic” and “static” targets. You can either use the Build Phases tab of the project editor or the Target Membership section of the File inspector.
+1. Audit new headers for nullability. Typically, you will wrap a header with `NS_ASSUME_NONNULL_BEGIN` and `NS_ASSUME_NONNULL_END`.
 1. _(Optional.)_ If it’s a public header, change its visibility from Project to Public and import it in [the iOS SDK’s umbrella header](./src/Mapbox.h).
 1. _(Optional.)_ If the file would also be used by the macOS SDK, make sure it’s in [platform/darwin/src/](../darwin/src/), then consult [the companion macOS document](../macos/DEVELOPING.md#adding-a-source-code-file) for further instructions.
 
diff --git a/platform/ios/INSTALL.md b/platform/ios/INSTALL.md
index bdda38946d..1f0975f477 100644
--- a/platform/ios/INSTALL.md
+++ b/platform/ios/INSTALL.md
@@ -4,12 +4,14 @@ This document explains how to build a development version of Mapbox iOS SDK for
 
 ### Requirements
 
-The Mapbox iOS SDK application builds against the iOS 7.0 SDK. It is intended to run on iOS 7.0 and above on the following devices and their simulators:
+The Mapbox iOS SDK builds against the iOS 7.0 SDK. It is intended to run on iOS 7.0 and above on the following devices and their simulators:
 
 * iPhone 4S and above (5, 5c, 5s, 6, 6 Plus)
 * iPad 2 and above (3, 4, Mini, Air, Mini 2, Air 2)
 * iPod touch 5th generation and above
 
+The Mapbox iOS SDK requires Xcode 7.3 or higher.
+
 ### Building the SDK
 
 1. [Install core dependencies](../../INSTALL.md).
diff --git a/platform/ios/docs/pod-README.md b/platform/ios/docs/pod-README.md
index 93aa18bc65..2d6134e6e0 100644
--- a/platform/ios/docs/pod-README.md
+++ b/platform/ios/docs/pod-README.md
@@ -10,6 +10,8 @@ For more information, check out the [Mapbox iOS SDK homepage](https://www.mapbox
 
 The Mapbox iOS SDK may be installed as either a dynamic framework or a static framework. (To reduce the download size, the static framework is omitted from some distributions; you may need to download the full package from the [release page](https://github.com/mapbox/mapbox-gl-native/releases/).)
 
+Integrating the Mapbox iOS SDK requires Xcode 7.3 or higher.
+
 {{DYNAMIC}}
 
 ### Dynamic framework
diff --git a/platform/ios/src/MGLAPIClient.h b/platform/ios/src/MGLAPIClient.h
index ef64b021b7..0f8926d360 100644
--- a/platform/ios/src/MGLAPIClient.h
+++ b/platform/ios/src/MGLAPIClient.h
@@ -3,10 +3,14 @@
 #import "MGLMapboxEvents.h"
 #import "MGLTypes.h"
 
+NS_ASSUME_NONNULL_BEGIN
+
 @interface MGLAPIClient : NSObject <NSURLSessionDelegate>
 
-- (void)postEvents:(nonnull NS_ARRAY_OF(MGLMapboxEventAttributes *) *)events completionHandler:(nullable void (^)(NSError * _Nullable error))completionHandler;
-- (void)postEvent:(nonnull MGLMapboxEventAttributes *)event completionHandler:(nullable void (^)(NSError * _Nullable error))completionHandler;
+- (void)postEvents:(NS_ARRAY_OF(MGLMapboxEventAttributes *) *)events completionHandler:(nullable void (^)(NSError * _Nullable error))completionHandler;
+- (void)postEvent:(MGLMapboxEventAttributes *)event completionHandler:(nullable void (^)(NSError * _Nullable error))completionHandler;
 - (void)cancelAll;
 
 @end
+
+NS_ASSUME_NONNULL_END
diff --git a/platform/ios/src/MGLAnnotationImage.h b/platform/ios/src/MGLAnnotationImage.h
index 5ded4016f7..a7003d7f91 100644
--- a/platform/ios/src/MGLAnnotationImage.h
+++ b/platform/ios/src/MGLAnnotationImage.h
@@ -1,7 +1,5 @@
 #import <UIKit/UIKit.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/ios/src/MGLAnnotationView.h b/platform/ios/src/MGLAnnotationView.h
index 5469841036..634e9ad723 100644
--- a/platform/ios/src/MGLAnnotationView.h
+++ b/platform/ios/src/MGLAnnotationView.h
@@ -1,7 +1,5 @@
 #import <UIKit/UIKit.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 @protocol MGLAnnotation;
diff --git a/platform/ios/src/MGLCalloutView.h b/platform/ios/src/MGLCalloutView.h
index 27d173b230..6918aad614 100644
--- a/platform/ios/src/MGLCalloutView.h
+++ b/platform/ios/src/MGLCalloutView.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 @protocol MGLCalloutViewDelegate;
diff --git a/platform/ios/src/MGLMapView+IBAdditions.h b/platform/ios/src/MGLMapView+IBAdditions.h
index f18df56e01..3766d044d8 100644
--- a/platform/ios/src/MGLMapView+IBAdditions.h
+++ b/platform/ios/src/MGLMapView+IBAdditions.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 @class MGLMapView;
 
 NS_ASSUME_NONNULL_BEGIN
diff --git a/platform/ios/src/MGLUserLocation.h b/platform/ios/src/MGLUserLocation.h
index 81f9557b16..f2243815cf 100644
--- a/platform/ios/src/MGLUserLocation.h
+++ b/platform/ios/src/MGLUserLocation.h
@@ -3,8 +3,6 @@
 
 #import "MGLAnnotation.h"
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/ios/src/MGLUserLocationAnnotationView.h b/platform/ios/src/MGLUserLocationAnnotationView.h
index 5e0a805f3a..15e37622d6 100644
--- a/platform/ios/src/MGLUserLocationAnnotationView.h
+++ b/platform/ios/src/MGLUserLocationAnnotationView.h
@@ -2,8 +2,6 @@
 #import <CoreLocation/CoreLocation.h>
 #import <Mapbox/Mapbox.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 @class MGLMapView;
diff --git a/platform/macos/DEVELOPING.md b/platform/macos/DEVELOPING.md
index 5f437f4172..412a58a140 100644
--- a/platform/macos/DEVELOPING.md
+++ b/platform/macos/DEVELOPING.md
@@ -4,7 +4,9 @@ This document explains how to build the Mapbox macOS SDK from source. It is inte
 
 ## Requirements
 
-The Mapbox macOS SDK and the macosapp demo application run on macOS 10.10.0 and above.
+The Mapbox macOS SDK and the macosapp demo application run on macOS 10.10.0 or above.
+
+The Mapbox macOS SDK requires Xcode 7.3 or above.
 
 ## Building the SDK
 
@@ -34,6 +36,7 @@ To add an Objective-C class, protocol, category, typedef, enumeration, or global
 To add an Objective-C header or implementation file to the macOS SDK:
 
 1. Add the file to the “dynamic” target’s Headers or Compile Sources build phase, as appropriate. You can either use the Build Phases tab of the project editor or the Target Membership section of the File inspector.
+1. Audit new headers for nullability. Typically, you will wrap a header with `NS_ASSUME_NONNULL_BEGIN` and `NS_ASSUME_NONNULL_END`.
 1. _(Optional.)_ If it’s a public header, change its visibility from Project to Public and import it in [the macOS SDK’s umbrella header](./src/Mapbox.h).
 1. _(Optional.)_ If the file would also be used by the iOS SDK, make sure it’s in [platform/darwin/src/](../darwin/src/), then consult [the companion iOS document](../ios/DEVELOPING.md#adding-a-source-code-file) for further instructions.
 
diff --git a/platform/macos/INSTALL.md b/platform/macos/INSTALL.md
index 07aae88a2e..665af128c5 100644
--- a/platform/macos/INSTALL.md
+++ b/platform/macos/INSTALL.md
@@ -4,7 +4,7 @@ This document explains how to build the Mapbox macOS SDK and integrate it into y
 
 ### Requirements
 
-The Mapbox macOS SDK requires the macOS 10.10.0 SDK or above.
+The Mapbox macOS SDK requires the macOS 10.10.0 SDK (or above) and Xcode 7.3 (or above).
 
 ### Building the SDK
 
diff --git a/platform/macos/src/MGLAnnotationImage.h b/platform/macos/src/MGLAnnotationImage.h
index ad44993ee1..37d43d7277 100644
--- a/platform/macos/src/MGLAnnotationImage.h
+++ b/platform/macos/src/MGLAnnotationImage.h
@@ -1,7 +1,5 @@
 #import <AppKit/AppKit.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /**
diff --git a/platform/macos/src/MGLMapView.h b/platform/macos/src/MGLMapView.h
index 9d44632196..fb2572ec08 100644
--- a/platform/macos/src/MGLMapView.h
+++ b/platform/macos/src/MGLMapView.h
@@ -1,6 +1,7 @@
 #import <Cocoa/Cocoa.h>
 #import <CoreLocation/CoreLocation.h>
 
+#import "MGLTypes.h"
 #import "MGLGeometry.h"
 
 NS_ASSUME_NONNULL_BEGIN
diff --git a/platform/macos/src/MGLMapViewDelegate.h b/platform/macos/src/MGLMapViewDelegate.h
index 6ea69f845a..c84ad42cf3 100644
--- a/platform/macos/src/MGLMapViewDelegate.h
+++ b/platform/macos/src/MGLMapViewDelegate.h
@@ -1,7 +1,5 @@
 #import <Foundation/Foundation.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 @class MGLMapView;
diff --git a/platform/macos/src/MGLOpenGLLayer.h b/platform/macos/src/MGLOpenGLLayer.h
index 5c8ac43e9e..832664f397 100644
--- a/platform/macos/src/MGLOpenGLLayer.h
+++ b/platform/macos/src/MGLOpenGLLayer.h
@@ -1,7 +1,5 @@
 #import <Cocoa/Cocoa.h>
 
-#import "MGLTypes.h"
-
 NS_ASSUME_NONNULL_BEGIN
 
 /// A subclass of NSOpenGLLayer that creates the environment mbgl needs to