[iOS] Enable developers to change position of ornaments (#13911)

* APIs for change position of ornaments

* Use anchors APIs and emove iOS8 layout code

* Add ornaments layout tests

1 files changed, 69 insertions, 0 deletions

diff --git a/platform/ios/src/UIView+MGLAdditions.m b/platform/ios/src/UIView+MGLAdditions.m
new file mode 100644
index 0000000000..43c54409bd
--- /dev/null
+++ b/platform/ios/src/UIView+MGLAdditions.m
@@ -0,0 +1,69 @@
+#import "UIView+MGLAdditions.h"
+
+@implementation UIView (MGLAdditions)
+
+- (UIViewController *)mgl_viewControllerForLayoutGuides
+{
+    // Per -[UIResponder nextResponder] documentation, a UIView’s next responder
+    // is its managing UIViewController if applicable, or otherwise its
+    // superview. UIWindow’s next responder is UIApplication, which has no next
+    // responder.
+    UIResponder *laterResponder = self;
+    while ([laterResponder isKindOfClass:[UIView class]])
+    {
+        laterResponder = laterResponder.nextResponder;
+    }
+    if ([laterResponder isKindOfClass:[UIViewController class]])
+    {
+        return (UIViewController *)laterResponder;
+    }
+    return nil;
+}
+
+- (NSLayoutYAxisAnchor *)mgl_safeTopAnchor {
+    if (@available(iOS 11.0, *)) {
+        return self.safeAreaLayoutGuide.topAnchor;
+    } else {
+        UIViewController *viewController = self.mgl_viewControllerForLayoutGuides;
+        BOOL useLayoutGuides = viewController.view && viewController.automaticallyAdjustsScrollViewInsets;
+        if (useLayoutGuides) {
+            return viewController.topLayoutGuide.bottomAnchor;
+        }
+        else {
+            return self.topAnchor;
+        }
+    }
+}
+
+- (NSLayoutXAxisAnchor *)mgl_safeLeadingAnchor {
+    if (@available(iOS 11.0, *)) {
+        return self.safeAreaLayoutGuide.leadingAnchor;
+    } else {
+        return self.leadingAnchor;
+    }
+}
+
+- (NSLayoutYAxisAnchor *)mgl_safeBottomAnchor {
+    if (@available(iOS 11.0, *)) {
+        return self.safeAreaLayoutGuide.bottomAnchor;
+    } else {
+        UIViewController *viewController = self.mgl_viewControllerForLayoutGuides;
+        BOOL useLayoutGuides = viewController.view && viewController.automaticallyAdjustsScrollViewInsets;
+        if (useLayoutGuides) {
+            return viewController.bottomLayoutGuide.topAnchor;
+        }
+        else {
+            return self.bottomAnchor;
+        }
+    }
+}
+
+- (NSLayoutXAxisAnchor *)mgl_safeTrailingAnchor {
+    if (@available(iOS 11.0, *)) {
+        return self.safeAreaLayoutGuide.trailingAnchor;
+    } else {
+        return self.trailingAnchor;
+    }
+}
+
+@end