[ios] Fix layout of Scale bar components (#15703)

* [ios] Add failing tests for scale bar updates.

* [ios] Remove borderLayer

* [ios] Ensure bar sections have non-fractional width

* [ios] Add RTL override

* [ios] Update constraints/layout

* [ios] Invalidate scalebars size, after the parent's layout has happened (to ensure the view dimensions are correct when re-laying out the scale bar.

* [ios] Refactor layout

* [ios] Update changelog / remove commented code.

* [ios] Remove whitespace

* [ios] Stop integration tests asserting (when scale bar is hidden). Also reduces the # of calculations (since updateConstraints and layoutSubviews can be called outside of our control).

* [ios] Moves declaration of properties for testing.

* [ios] Removes redundant property attribute

* [ios] Updated change log

1 files changed, 9 insertions, 12 deletions

diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index 62b943fd3d..76cec479bb 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -852,9 +852,11 @@ public:
             break;
     }
 
-    [updatedConstraints addObject:[view.widthAnchor constraintEqualToConstant:size.width]];
-    [updatedConstraints addObject:[view.heightAnchor constraintEqualToConstant:size.height]];
-
+    if (!CGSizeEqualToSize(size, CGSizeZero)) {
+        [updatedConstraints addObject:[view.widthAnchor constraintEqualToConstant:size.width]];
+        [updatedConstraints addObject:[view.heightAnchor constraintEqualToConstant:size.height]];
+    }
+    
     [NSLayoutConstraint deactivateConstraints:constraints];
     [constraints removeAllObjects];
     [NSLayoutConstraint activateConstraints:updatedConstraints];
@@ -883,7 +885,7 @@ public:
     [self updateConstraintsForOrnament:self.scaleBar
                            constraints:self.scaleBarConstraints
                               position:self.scaleBarPosition
-                                  size:self.scaleBar.intrinsicContentSize
+                                  size:CGSizeZero
                                margins:self.scaleBarMargins];
 }
 
@@ -929,15 +931,14 @@ public:
 // This gets called when the view dimension changes, e.g. because the device is being rotated.
 - (void)layoutSubviews
 {
+    [super layoutSubviews];
+
     // Calling this here instead of in the scale bar itself because if this is done in the
     // scale bar instance, it triggers a call to this `layoutSubviews` method that calls
     // `_mbglMap->setSize()` just below that triggers rendering update which triggers
     // another scale bar update which causes a rendering update loop and a major performace
-    // degradation. The only time the scale bar's intrinsic content size _must_ invalidated
-    // is here as a reaction to this object's view dimension changes.
+    // degradation.
     [self.scaleBar invalidateIntrinsicContentSize];
-    
-    [super layoutSubviews];
 
     [self adjustContentInset];
 
@@ -6642,11 +6643,7 @@ public:
     // setting this property.
     if ( ! self.scaleBar.hidden)
     {
-        CGSize originalSize = self.scaleBar.intrinsicContentSize;
         [(MGLScaleBar *)self.scaleBar setMetersPerPoint:[self metersPerPointAtLatitude:self.centerCoordinate.latitude]];
-        if ( ! CGSizeEqualToSize(originalSize, self.scaleBar.intrinsicContentSize)) {
-            [self installScaleBarConstraints];
-        }
     }
 }