Revert "[ios] Removed MGLAnnotationView.flat"

This reverts commit f2fdc23ec7b39d1ee6c9e4b37ad4952e4a5f5447.

3 files changed, 20 insertions, 0 deletions

diff --git a/platform/ios/Mapbox.playground/Contents.swift b/platform/ios/Mapbox.playground/Contents.swift
index 1f368be73b..8f4c574fc1 100644
--- a/platform/ios/Mapbox.playground/Contents.swift
+++ b/platform/ios/Mapbox.playground/Contents.swift
@@ -118,6 +118,7 @@ class MapDelegate: NSObject, MGLMapViewDelegate {
             let av = PlaygroundAnnotationView(reuseIdentifier: "annotation")
             av.frame = CGRect(x: 0, y: 0, width: 30, height: 30)
             av.centerOffset = CGVector(dx: -15, dy: -15)
+            av.flat = true
             let centerView = UIView(frame: CGRectInset(av.bounds, 3, 3))
             centerView.backgroundColor = UIColor.whiteColor()
             av.addSubview(centerView)
diff --git a/platform/ios/app/MBXViewController.m b/platform/ios/app/MBXViewController.m
index 29c5c65012..2fb38a5350 100644
--- a/platform/ios/app/MBXViewController.m
+++ b/platform/ios/app/MBXViewController.m
@@ -1720,6 +1720,10 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
         // method in this class to make draggable annotation views play nice.
         annotationView.draggable = YES;
 
+        // uncomment to flatten the annotation view against the map when the map is tilted
+        // this currently causes severe performance issues when more than 2k annotations are visible
+        // annotationView.flat = YES;
+        
         // Uncomment to force annotation view to maintain a constant size when
         // the map is tilted. By default, annotation views will shrink and grow
         // as they move towards and away from the horizon. Relatedly, annotations
diff --git a/platform/ios/src/MGLAnnotationView.h b/platform/ios/src/MGLAnnotationView.h
index 2802d31b05..2a1a118d76 100644
--- a/platform/ios/src/MGLAnnotationView.h
+++ b/platform/ios/src/MGLAnnotationView.h
@@ -155,6 +155,21 @@ typedef NS_ENUM(NSUInteger, MGLAnnotationViewDragState) {
 @property (nonatomic) CGVector centerOffset;
 
 /**
+ A Boolean value indicating whether the view lies flat against the map as it
+ tilts.
+ 
+ If this option is unset, the annotation view remains unchanged as the map’s
+ pitch increases, so that the view appears to stand upright on the tilted map.
+ If this option is set, the annotation view tilts as the map’s pitch increases,
+ so that the view appears to lie flat against the tilted map.
+ 
+ For example, you would set this option if the annotation view depicts an arrow
+ that should always point due south. You would unset this option if the arrow
+ should always point down towards the ground.
+ */
+@property (nonatomic, assign, getter=isFlat) BOOL flat;
+
+/**
  A Boolean value that determines whether the annotation view grows and shrinks
  as the distance between the viewpoint and the annotation view changes on a
  tilted map.