[ios] Always show annotation view even when view reuse is not used

This fixes an issue where the map view would drop annotation views
if the developer did not make full use of the reuse queue. The
fixes are:

- Guard against enqueuing a view for reuse if it does not have
a `viewReuseIdentifier`. Previously, if the app developer created a new
annotation view with no reuse id each time
`[MGLMapViewDelegate mapView:viewForAnnotation:]` was called and then
the view was scrolled offscreen, we  attempted to add the view to the
reuse queue (for no good reason) and  did not update the views center
ever again.  This change avoids the reuse queue and just updates the
center always.

- Add any annotation view that should be displayed but is not in the
annotation container view to the annotation container view. Previously,
if the app developer created a new annotation view with a reuse id
each time `[MGLMapViewDelegate mapView:viewForAnnotation:]` was called,
and then if the annotation was scrolled off and then on screen again,
we did not add the new view to the container view because it was
not happening in the normal `addAnnotation` cycle. This adds add
logic to catch that case and add annotation views created in this
way to the view.

1 files changed, 5 insertions, 1 deletions

diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 273f2715fa..f2a365f455 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -4572,6 +4572,10 @@ public:
                 annotationView.mapView = self;
                 annotationView.center = [self convertCoordinate:annotationContext.annotation.coordinate toPointToView:self];
                 annotationContext.annotationView = annotationView;
+                
+                if (!annotationView.superview) {
+                    [self.annotationContainerView insertSubview:annotationView atIndex:0];
+                }
             }
             else
             {
@@ -4581,7 +4585,7 @@ public:
         }
         
         bool annotationViewIsVisible = CGRectContainsRect(viewPort, annotationView.frame);
-        if (!annotationViewIsVisible)
+        if (!annotationViewIsVisible && annotationContext.viewReuseIdentifier)
         {
             [self enqueueAnnotationViewForAnnotationContext:annotationContext];
         }