From 68a9e2ea926db80010ade77cda77ced53d412b28 Mon Sep 17 00:00:00 2001
From: Jason Wray <jason@mapbox.com>
Date: Fri, 5 Jan 2018 04:06:44 -0500
Subject: [PATCH] [ios] Provide haptic feedback when user rotates to due north

---
 platform/ios/CHANGELOG.md      |  1 +
 platform/ios/src/MGLMapView.h  | 13 +++++++++++++
 platform/ios/src/MGLMapView.mm | 21 +++++++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/platform/ios/CHANGELOG.md b/platform/ios/CHANGELOG.md
index 9eb522f2b..b0f3e741e 100644
--- a/platform/ios/CHANGELOG.md
+++ b/platform/ios/CHANGELOG.md
@@ -48,6 +48,7 @@ Mapbox welcomes participation and contributions from everyone. Please read [CONT
 * Labels are now transliterated from more languages when VoiceOver is enabled. ([#10881](https://github.com/mapbox/mapbox-gl-native/pull/10881))
 * Long-pressing the attribution button causes the SDK’s version number to be displayed in the action sheet that appears. ([#10650](https://github.com/mapbox/mapbox-gl-native/pull/10650))
 * Reduced offline download size for styles with symbol layers that render only icons, and no text. ([#11055](https://github.com/mapbox/mapbox-gl-native/pull/11055))
+* Added haptic feedback that occurs when the user rotates the map to due north, configurable via `MGLMapView.hapticFeedbackEnabled`. ([#10847](https://github.com/mapbox/mapbox-gl-native/pull/10847))
 
 ## 3.7.5 - February 16, 2018
 
diff --git a/platform/ios/src/MGLMapView.h b/platform/ios/src/MGLMapView.h
index 9c18965b0..44130f3c6 100644
--- a/platform/ios/src/MGLMapView.h
+++ b/platform/ios/src/MGLMapView.h
@@ -483,6 +483,19 @@ MGL_EXPORT IB_DESIGNABLE
  */
 @property(nonatomic, getter=isPitchEnabled) BOOL pitchEnabled;
 
+/**
+ A Boolean value that determines whether the user will receive haptic feedback
+ for certain interactions with the map.
+
+ When this property is set to `YES`, the default, a `UIImpactFeedbackStyleLight`
+ haptic feedback event be played when the user rotates the map to due north
+ (0°).
+
+ This feature requires a device that supports haptic feedback, running iOS 10 or
+ newer.
+ */
+@property(nonatomic, getter=isHapticFeedbackEnabled) BOOL hapticFeedbackEnabled;
+
 /**
  A floating-point value that determines the rate of deceleration after the user
  lifts their finger.
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 1cb477955..bb8948150 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -228,6 +228,7 @@ public:
 @property (nonatomic) CGFloat quickZoomStart;
 @property (nonatomic, getter=isDormant) BOOL dormant;
 @property (nonatomic, readonly, getter=isRotationAllowed) BOOL rotationAllowed;
+@property (nonatomic) BOOL shouldTriggerHapticFeedbackForCompass;
 @property (nonatomic) MGLMapViewProxyAccessibilityElement *mapViewProxyAccessibilityElement;
 @property (nonatomic) MGLAnnotationContainerView *annotationContainerView;
 @property (nonatomic) MGLUserLocation *userLocation;
@@ -525,6 +526,8 @@ public:
     [_twoFingerTap requireGestureRecognizerToFail:_twoFingerDrag];
     [self addGestureRecognizer:_twoFingerTap];
 
+    _hapticFeedbackEnabled = YES;
+
     _decelerationRate = MGLMapViewDecelerationRateNormal;
 
     _quickZoom = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleQuickZoomGesture:)];
@@ -1513,6 +1516,8 @@ public:
             self.userTrackingMode = MGLUserTrackingModeFollow;
         }
 
+        self.shouldTriggerHapticFeedbackForCompass = NO;
+
         [self notifyGestureDidBegin];
     }
     else if (rotate.state == UIGestureRecognizerStateChanged)
@@ -1535,6 +1540,22 @@ public:
         }
 
         [self cameraIsChanging];
+
+        // Trigger a light haptic feedback event when the user rotates to due north.
+        if (@available(iOS 10.0, *))
+        {
+            if (self.isHapticFeedbackEnabled && fabs(newDegrees) <= 1 && self.shouldTriggerHapticFeedbackForCompass)
+            {
+                UIImpactFeedbackGenerator *hapticFeedback = [[UIImpactFeedbackGenerator alloc] initWithStyle:UIImpactFeedbackStyleLight];
+                [hapticFeedback impactOccurred];
+
+                self.shouldTriggerHapticFeedbackForCompass = NO;
+            }
+            else if (fabs(newDegrees) > 1)
+            {
+                self.shouldTriggerHapticFeedbackForCompass = YES;
+            }
+        }
     }
     else if (rotate.state == UIGestureRecognizerStateEnded || rotate.state == UIGestureRecognizerStateCancelled)
     {